Parallel link mechanism, exposure system and method of manufacturing the same, and method of manufacturing devices

ABSTRACT

A reticle base level block to support a reticle stage for holding a reticle, a wafer base level block to support a wafer stage for holding a wafer, and the like are supported to be independent of other portions and be controllable in their attitudes by parallel link mechanisms each including at least three expandable rods. Therefore, the portions supported by the parallel link mechanism can be made lightweight using the advantages of the parallel link mechanism, and the attitudes of those can be precisely controlled with excellent operational-characteristics and high rigidity. In addition, transmission of vibrations and the like between the reticle base level block, the wafer base level block and other portions, e.g. an optical projection system, can be prevented. Therefore, a fine pattern formed on the reticle can be precisely transferred onto the wafer.

TECHNICAL FIELD

The present invention relates to a parallel link mechanism, an exposureapparatus and its making method, and a method of manufacturing a deviceand, more specifically, to a parallel link mechanism, a kind ofmechanism, to employ at least three expandable rods and control theposition/attitude of a movable object, an exposure apparatus employingthe parallel link mechanism to control the attitude of at least one of amask and a substrate and its making method, and a method ofmanufacturing a micro device (electronic device) by using the exposureapparatus.

BACKGROUND ART

In a lithography process for manufacturing a semiconductor element,liquid crystal display element, or the like, an exposure apparatus hasbeen used. A reduction projection exposure apparatus (stepper), of astep-and-repeat method, which transfers a pattern formed on a mask orreticle (to be generically referred to as a “reticle” hereinafter)through a projection optical system onto a plurality of shot areas on asubstrate such as a wafer or glass plate (to be referred to as a “wafer”hereinafter) in turn, and a moving-one-by-one type projection exposureapparatus (to be referred to as a “stepper” hereinafter as needed) suchas a scanning projection exposure apparatus (scanning-stepper), of astep-and-scan method, which is obtained by improving the reductionprojection exposure apparatus are mainly employed.

Important ones of the basic factors to determine the performance of thestepper are the resolution ability (resolution) and focus depth of theprojection optical system (projection lens). It is because theresolution determines the finest pattern size that can be projected andimaged, i.e. the narrowest line width in practice (device rule). And itsfocus depth has to be as wide as possible because a processed wafer hassteps formed thereon by forming and etching thin layers of oxide, metal,etc., and may be slightly deformed.

The resolution R and focus depth DOF of a projection lens is given bythe following two equations as a general measure:R=k1·λ/N.A.  (1)DOF=k2·λ/(N.A.)²  (2)

Note that λ, N.A. and k1, k2 respectively represent the wavelength oflight used for exposure, the numerical aperture of the projectionoptical system, and parameters determined by resist, etc.

An early stepper used a g-line (λ=436 nm) of an ultra-high pressuremercury lamp as exposure illumination light; its N.A. was about 0.3, andits resolution was about 1.2 um. As obvious in the above equation (1),the larger the N.A. is, the better the resolution is. With a largerN.A., however, the focus depth is decreased as obvious in the aboveequation (2).

Therefore, apparatuses for production of 16 Mbit DRAM and apparatusesfor the later have achieved high resolution by using i-line (λ=365 nm)and a projection optical system of which N.A. is about 0.5, and alsohave achieved a practical focus depth. Because the i-line can beobtained from an ultra-high pressure mercury lamp like the g-line andcan be used in the same way as earlier steppers in semiconductormanufacturing factories, the i-line steppers have been introduced as aproduction unit more smoothly than expected.

After that, in the period from the third generation of 64 Mbit DRAM to245 Mbit DRAM where their device rules are equal to or less than 0.3 um,instead of the mercury lamp as a light source, the use of KrF excimerlaser was examined, and the application of a phase shift reticle andmodified illumination that can be applied by improving then currentunits was suggested.

While a KrF excimer laser (λ=248 nm) stepper uses a common basic bodywith a previous stepper using g-line or i-line, its optical system fromthe source to the projection optical system is different. That is,because using light of a shorter wavelength, usable optical materialsare limited to quartz, fluorite, etc. In addition, because excimer laserlight is pulse emission light and coherent unlike that of a mercurylamp, a special technology for the illumination system is necessary.

Because interference fringe induced by the coherency of the excimerlaser affects the precision of line width of an exposure pattern, it isnecessary to suppress the effects of the interference fringe byproviding a vibrating mirror in the illumination optical system andmaking a light beam fluctuate finely. In a stepper with a lamp as itslight source, accumulated exposure amount can be controlled by theopen/close time of its shutter. Meanwhile, in a laser-light-sourcestepper using pulse emission, it is necessary to set the number ofpulses per an exposure to be equal to or more than a certain number(referred to as a minimum exposure-pulse number) to compensate forenergy fluctuation.

For 1 Gbit DRAM of the future where device rules will be equal to orless than 0.2 um, the use of ArF excimer laser (λ=193 nm), phase shiftreticle and modified illumination technology is suggested. An ArFexcimer laser stepper needs to have the optical path of its exposurelight filled with nitrogen or the like because the exposure light isabsorbed by oxygen.

To obtain even higher resolution and wider focus depth, light source ofa shorter wavelength can be used leaving N.A. of the projection opticalsystem as it is. Recently, reduction projection lithography using F₂(λ=157 nm) laser having a shorter wavelength than ArF excimer laser asits light source is presented by MIT Lincoln Lab., and is attracting alot of attention. Because F₂ laser light is absorbed by oxygen like ArFexcimer laser light, exposure needs to be performed in the atmosphere ofN₂ or He.

Furthermore, to improve the precision of an exposure apparatus usinglight source of such a short wavelength, the precision of positioning ofa reticle stage and wafer stage needs to be improved, and it is alsonecessary to suppress vibrations of units due to reaction caused by thedrive of the stages as movable objects as much as possible and insulatefloor vibrations.

Therefore, to realize highly precise exposure using such ashort-wavelength light source as F₂ laser, it is necessary to controlpositioning, and suppressing or insulating vibrations more preciselythan ever.

For example, as factors required of a scanning stepper that transfersthe reticle pattern onto a plurality of shot areas on the wafer in turnaccording to a step-and-scan method by repeating a scanning exposureoperation, in which a reticle pattern is transferred onto the wafersynchronously moving the reticle stage holding the reticle and the waferstage holding the wafer in one dimensional direction, and astepping-between-shots operation of the wafer stage, there are thefollowing things: [1] The driving reactions of the stages do nottransmit to the frame supporting the projection optical system; [2] Itis easy to adjust relative position and attitude between each of thestages and the projection optical system; [3] The driving thrust anddriving reaction are reduced by making the stages lightweight; [4] It isso structured that floor vibrations are prevented from transmitting tothe stages and the projection optical system; [5] It is so structuredthat the stages and the projection optical system can be easilyseparated. [1] to [4] are required to realize precise exposure of a finepattern, and [5] is required to improve easiness of its maintenance andreduce its down-time so that the productivity of a micro device isimproved.

Also, there is a double wafer-stage scheme for realizing the highthroughput where two wafer stages are mounted on the level block; whilea wafer stage is performing exposure, the other performs alignment orthe like and the two operations are alternately and continuouslyperformed. Furthermore, a multi-exposure method such as a doubleexposure method where using two reticle stages each holding a reticlehaving a pattern different from the other formed thereon, those patternsare transferred in turn is effective for higher integration ofsemiconductor devices because it is possible to improve the resolutionand focus depth. Note that to achieve a desirable effect in the doublewafer-stage scheme and the multi-exposure method, the above factors [1]to [4] have to be satisfied as a premise, and that it is preferable tosatisfy the above factor [5].

In addition, when performing exposure using light of a wave lengthshorter than or equal to F₂ laser light, [6] it is required that thestages, the projection optical system, and the like should be containedby a chamber so as to be enclosed in the atmosphere of N₂ or He.

Also, in a step-and-repeat type stepper, it is preferable to satisfy theabove factors [1] to [6], not to mention.

Of the above factors [1] to [6], the factor [3] can be satisfied byadopting a planar motor or a cylinder-like linear motor as drivingsources of the stages. Especially, when adopting the planar motor as adriving source of the wafer stage, the planar motor can drive themovable object in three degrees of freedom X, Y, θz by one motor, andtherefore, X guide and Y guide of X-Y two dimensional arrangement thatwere previously indispensable are unnecessary. And when driving thestage holding the wafer in one direction of X-axis and Y-axisdirections, a motor and a guide for driving the stage in the otherdirection need not be driven along with the stage, and therefore, theweight of the movable portion can be remarkably reduced. Therefore, itis attracting a lot of attention as a promising driving source of thewafer stage of an exposure apparatus in the future.

However, it is very difficult to satisfy the rest, [1], [2], [4], [5],[6], at the same time even if the planar motor is adopted as a drivingsource of the stage.

Meanwhile, as means of moving the movable portion in the six degrees offreedom regarding translation and rotation, a mechanism referred to as asteward-platform, a kind of parallel mechanism (also referred to as aparallel link mechanism) where a base portion and end-effecter areconnected by a plurality of link chains each having more than twojoints, is used in training and simulation of flying an air plane, andis attracting attention in the field of industrial robots.

The present invention is invented under such a circumstance and a firstpurpose of the present invention is to provide a parallel link mechanismthat can realize the miniaturization/lightening and the improvement ofthe output at the same time.

Furthermore, a second purpose of the present invention is to provide anexposure apparatus that can precisely transfer a fine pattern onto asubstrate and a method of making the exposure apparatus.

In addition, a third purpose of the present invention is to provide amethod of manufacturing a highly integrated micro-device with highproductivity.

DISCLOSURE OF INVENTION

Under the above circumstance, the inventors of the present inventionhave conducted studies to realize such an exposure apparatus assatisfies as many of the above factors ([1] to [6] as possible at thesame time regardless of whether a planar motor is adopted as a stagedriving source or not. And as a result, they have reached a conclusionthat the objective can be achieved by leaving out a body (centralcolumn) that has been used in the previous exposure apparatuses,supporting respectively the reticle stage, the wafer stage, etc., to bedependent, and making it possible to control their positions/attitudesin six degrees of freedom to meet any requirement. With such aconclusion and further studies, they have thought of applying the abovemechanism to the exposure apparatuses.

Then by elaborately examining the parallel mechanism (hereafter,referred to as a “parallel link mechanism”), it is found that althoughit can satisfy most of the factors, which the inventors intend, such asthe movable portion being lightweight and having desirableoperational-characteristics, high rigidity, and precision ofpositioning, there are some points to be improved because an oilcylinder is used as an active contrapostion in a steward-platform,representative of parallel mechanisms.

According to the first aspect of the present invention, there isprovided a parallel link mechanism comprising a base member; at leastthree expandable rods each including a first axis member and a secondaxis member that can relatively move in their axis direction; expansionmechanisms that are arranged in the respective rods and expand/contractthe respective rods each by relatively driving the first axis member andthe second axis member in the axis direction, each of which comprises ashaft motor that comprises a cylindrical mover integrally arranged inone of the first axis member and the second axis member, and a columnarstator integrally arranged in the other of the first axis member and thesecond axis member, and that relatively drives the first axis member andthe second axis member in the axis direction by using thrust generatedby electromagnetic interaction between the first axis member and thesecond axis member.

With this shaft motor, because a columnar or cylindrical magnet is usedin its mover side or stator side, magnetic flux (magnetic field) isgenerated radially and in all directions, and the exposure apparatus canhave the whole magnetic flux in all directions contribute to thegeneration of a driving force by an electromagnetic or magneticinteraction. And then much larger thrust can be generated compared withan usual linear motor, etc. and it is possible to make it smaller than ahydraulic cylinder, etc. In this case, either stator can be used, ahollow column or a solid column.

Therefore, by using the parallel link mechanism according to the presentinvention that comprises expansion mechanisms that are arranged in therespective rods and each comprise the shaft motor, which comprises acylindrical mover integrally arranged in one of the first axis memberand the second axis member, and a columnar stator integrally arranged inthe other of the first axis member and the second axis member, andrelatively drives the first axis member and the second axis member inthe axis direction by using thrust generated by electromagneticinteraction between the first axis member and the second axis member,the miniaturization and lightening, and the improvement of the outputcan be realized at the same time. The parallel link mechanism accordingto the present invention is preferably applied to exposure apparatuses.

In the parallel link mechanism according to the present invention, theexpansion mechanism can comprise an air cylinder arranged in parallel orin series with the shaft motor. In such a case, the movable body can bedriven coarsely and by larger distances by controlling the air pressureof the air cylinder, and also finely by the shaft motor. Also, in thiscase, it is possible to use the air cylinder to expand/contract each rodfor controlling the position/attitude of the movable body, to use theshaft motor to suppress vibrations, and to use the air cylinder forsuppressing low-frequency vibrations and the shaft motor for insulatinghigh-frequency vibrations.

According to the second aspect of the present invention, there isprovided an exposure apparatus, which transfers a predetermined patternonto a substrate, comprising a exposure main portion for transferringthe pattern; and a parallel link mechanism that supports at least a partof the exposure main portion in such a way that its attitude iscontrollable.

By using this, because a part of the exposure main portion thattransfers a predetermined pattern onto a substrate is supported by theparallel link mechanism in such a way that its attitude is controllable,the part of the exposure main portion supported by the parallel linkmechanism can be made lightweight by using the advantages of theparallel link mechanism and its attitude can be precisely controlledwith desirable operational-characteristics and high rigidity. Inaddition, because the part of the exposure main portion can be supportedto be independent of other portions by the parallel link mechanism, thetransmission of vibrations, etc., can be prevented. Especially, in acase where a movable portion of a substrate stage or the like composingthe exposure main portion is supported by the parallel link mechanism,such effects to others as vibrations due to the drive of the movableportion can be reduced. Therefore, by using the exposure main portionaccording to the present invention, a fine pattern can be preciselytransferred onto a substrate.

In an exposure apparatus according to the present invention, theexposure main portion comprises a substrate stage to hold the substrateand it is possible to have the parallel link mechanism control theposition/attitude in at least three degrees of freedom of the substratestage. In such a case, because the parallel link mechanism controls theposition/attitude in at least three degrees of freedom of the substratestage, the substrate stage driven by the parallel link mechanism can bemade lightweight and the position/attitude in at least three degrees offreedom of the substrate can be precisely controlled with desirableoperational-characteristics and high rigidity.

In this case, the parallel link mechanism may comprise a first basemember, at least three expandable first rods that link the first basemember and the substrate stage, and first expansion mechanisms that arearranged in the respective first rods and expand/contract the respectivefirst rods. In such a case, by expanding and contracting the respectiverods by the first expansion mechanisms that are arranged in therespective first rods, the position/attitude, in at least three degreesof freedom (e.g. X, Y, θz), of the substrate stage can be preciselycontrolled with desirable operational-characteristics and high rigidity.In this case, because the substrate stage is driven by the parallel linkmechanism, such a driver to drive the substrate stage as a linear motor,a stage base (wafer base level block) to support the wafer stage, andthe like are unnecessary. Note that for controlling theposition/attitude in six degrees of freedom of the substrate, it isnecessary to provide a driving mechanism (e.g. Z-tilt mechanism), whichdrives the substrate in the other degrees of freedom (e.g. Z, θx, θy),and the like on the substrate stage.

In this case, it is preferable that the parallel link mechanismcomprises six of the first rods and controls position/attitude, in sixdegrees of freedom, of the substrate stage by expansion/contraction ofeach first rod. In such a case, because the position/attitude, in thesix degrees of freedom, of the substrate stage can be controlled byindividual expansions/contractions of the six first rods of the parallellink mechanism, the above Z-tilt mechanism, etc., are unnecessary andtherefore, it is possible to make the substrate stage, as the movableportion, more lightweight.

In an exposure apparatus according to the present invention, the firstexpansion mechanism may comprise an air cylinder and an electromagneticlinear motor that are arranged in parallel or in series with each other.In such a case, the substrate stage can be driven coarsely and by largerdistances by controlling the air pressure of the air cylinder, and alsofinely by the electromagnetic linear motor, and it is possible toprecisely control the position/attitude, in at least three degrees offreedom, of the substrate stage for a short time.

In an exposure apparatus according to the present invention, theexposure main portion may comprise a projection optical system thatprojects the pattern onto the substrate as well as the substrate stagethe position/attitude of which, in at least three degrees of freedom, iscontrolled by at least three first rods. In this case, by individuallyexpanding and contracting the first rods by the respective firstexpansion mechanisms and controlling the position/attitude, in at leastthree degrees of freedom, of the substrate stage, the relative position,in at least three degrees of freedom, between the projection opticalsystem and the substrate stage can be precisely adjusted with desirableoperational-characteristics and high rigidity.

In this case, the exposure main portion may further comprise a maskstage to hold the mask on which the pattern is formed and the parallellink mechanism may control the position/attitude in at least threedegrees of freedom of the mask stage. In such a case, because theparallel link mechanism controls the position/attitude in at least threedegrees of freedom of the mask stage, the mask stage driven by theparallel link mechanism can be made lightweight and theposition/attitude in at least three degrees of freedom of the mask stagecan be precisely controlled with desirable operational-characteristicsand high rigidity and it is possible to adjust the relative position, inat least three degrees of freedom (e.g. X, Y, θz or Z, θx, θy), betweenthe mask stage and the projection optical system.

In this case, the parallel link mechanism may comprise a second basemember, at least three expandable second rods that link the second basemember and the mask stage, and second expansion mechanisms that arearranged in the respective second rods and expand/contract therespective second rods. In such a case, by expanding and contracting therespective rods by the second expansion mechanisms that are arranged inthe respective second rods, the control of the position/attitude, in atleast three degrees of freedom (e.g. X, Y, θz), of the mask stage andthe adjustment of the relative position, in at least three degrees offreedom (e.g. X, Y, θz or Z, θx, θy), between the mask stage and theprojection optical system can be precisely performed with desirableoperational-characteristics and high rigidity. In this case, because themask stage is driven by the parallel link mechanism, such a driver todrive the mask stage as a linear motor, a stage base to support the maskstage, and the like are unnecessary. Note that for controlling theposition/attitude in six degrees of freedom of the mask, it is necessaryto provide a driving mechanism (e.g. a Z-tilt mechanism or a planarmotor) or the like which drives the mask in the other degrees of freedom(e.g. Z, θx, θy or Z, θx, θy), on the mask stage.

In this case, it is preferable that the parallel link mechanismcomprises six of the second rods and controls the position/attitude, insix degrees of freedom, of the mask stage by expansion/contraction ofeach second rod. In such a case, because the position/attitude, in thesix degrees of freedom, of the mask stage can be controlled byindividual expansions/contractions of the six second rods of theparallel link mechanism, the above Z-tilt mechanism, planar motor, etc.,are unnecessary, and therefore, it is possible to make the mask stage,as the movable portion, more lightweight.

In an exposure apparatus according to the present invention, in a casewhere the parallel link mechanism comprises at least three of the firstrods expanded and contracted by the first expansion mechanisms tocontrol the position/attitude of the substrate stage and at least threeof the second rods expanded and contracted by the second expansionmechanisms to control the position/attitude of the mask stage, at leastone of the first and second expansion mechanisms may comprise an aircylinder and an electromagnetic linear motor that are arranged inparallel or in series with each other. In such a case, at least one ofthe substrate stage and the mask stage can be driven coarsely and bylarger distances by controlling the air pressure of the air cylinder,and also finely by the electromagnetic linear motor, and it is possibleto precisely control the position/attitude, in at least three degrees offreedom, of at least one of the substrate stage and the mask stage andprecisely adjust the relative position of at least one stage withrespect to the projection optical system for a short time.

In this case, it is preferable that at least one of the first and secondrods further comprises a bearing unit to support the mover of theelectromagnetic linear motor with respect to its stator in a non-contactmanner. In such a case, because friction that works as a non-linearcomponent upon controlling the expansion/contraction of the rod havingthe bearing unit by the expansion mechanism can be avoided, theposition/attitude, in three degrees of freedom, of at least one of thewafer stage and the mask stage can be more precisely controlled.

Note that in this case, either of a gas static pressure bearing unit anda magnetic bearing unit can be used as the bearing unit.

When a gas static pressure bearing unit is used as the bearing unit, itis preferable that a differential exhaust mechanism is arranged in itsneighbor so that a gas supplied to the gas static pressure bearing unitdoes not contaminate the gas purity of the atmosphere inside theexposure apparatus.

In an exposure apparatus according to the present invention, therelative position between at least one of both the stages and theprojection optical system may be statically adjusted by using the aircylinder, and also a controller to suppress vibrations by using theelectromagnetic linear motor may be provided. In such a case, it ispossible to adjust the relative position between at least one of boththe stages and the projection optical system and suppress vibrations dueto expansion/contraction of each rod.

An exposure apparatus according to the present invention may furthercomprise a controller that insulates high-frequency vibrations bycontrolling the current of the electromagnetic linear motor. In such acase, fine vibrations from the floor surface, high-frequency vibrations,can be insulated.

An exposure apparatus according to the present invention may furthercomprise a supporting mechanism that supports the projection opticalsystem to be in a fixed state on the floor surface on which the exposuremain portion is mounted. In such a case, by having the supportingmechanism support it to be fixed immediately after the initialadjustment of the projection optical system to take a desirable positionand attitude, the relative positions, in at least three degrees offreedom, of both the stages with respect to the projection opticalsystem can be adjusted because it is possible to control thepositions/attitudes, in at least three degrees of freedom, of thesubstrate stage and the mask stage.

In an exposure apparatus according to the present invention, in a casewhere the parallel link mechanism comprises the first and second basemembers, at least three of the first rods expanded and contracted by thefirst expansion mechanisms, and at least three of the second rodsexpanded and contracted by the second expansion mechanisms, the parallellink mechanism may further comprise a third base member, at least threeexpandable third rods that link the third base member and the projectionoptical system, and third expansion mechanisms that are arranged in therespective third rods and expand/contract the respective third rods. Insuch a case, by individually controlling expansion mechanisms arrangedin the respective third rods upon the initial adjustment of theprojection optical system, the initial adjustment can be easilyperformed. After the initial adjustment, by keeping the lengths of therespective third rods by the third expansion mechanisms, the projectionoptical system can be supported and fixed to be in a desirable positionand attitude. After that, the relative position, in at least threedegrees of freedom, between each stage and the projection optical systemis adjusted by controlling the position/attitude of each stage.

In this case, the third expansion mechanism may comprise an aircylinder. In such a case, the initial adjustment of theposition/attitude of the projection optical system can be easilyperformed by adjusting the inside pressure of the air cylinder.

In an exposure apparatus according to the present invention, the first,second, and third base members may each be an individual member, or atleast two of the first, second, and third base members may be one commonmember. That is, the first, second, and third base members may be onecommon member, or the first and second base members, the second andthird base members, or the first and third base members may be onecommon member.

In an exposure apparatus according to the present invention, it ispossible to have the exposure main portion comprise a mask stage to holda mask on which the pattern is formed and to make the parallel linkmechanism control the relative position, in three degrees of freedom, ofthe mask stage. In such a case, because the parallel link mechanismcontrols the position/attitude, in at least three degrees of freedom, ofthe mask stage, it is possible to make the mask stage driven by theparallel link mechanism lightweight and the position/attitude, in atleast three degrees of freedom (e.g. X, Y, θz or Z, θx, θy), of the maskstage can be precisely controlled with desirableoperational-characteristics and high rigidity. Note that when theexposure main portion comprises the projection optical system, it ispossible to adjust the relative position, in at least three degrees offreedom, between the mask stage and the projection optical system.

In this case, the parallel link mechanism may comprise a base member, atleast three expandable rods that link the base member and the maskstage, and expansion mechanisms that are arranged in the respectivesecond rods and expand/contract the respective rods. In such a case, byexpanding and contracting the respective rods by the expansionmechanisms that are arranged in the respective rods, the control of theposition/attitude, in at least three degrees of freedom (e.g. X, Y, θz),of the mask stage can be precisely performed with desirableoperational-characteristics and high rigidity. In this case, because themask stage is driven by the parallel link mechanism, such a driver todrive the mask stage as a linear motor, a stage base to support the maskstage, and the like are unnecessary. Note that for controlling theposition/attitude in six degrees of freedom of the mask, it is necessaryto provide a driving mechanism (e.g. a Z-tilt mechanism), which drivesthe mask in the other degrees of freedom (e.g. Z, θx, θy), and the likeon the mask stage.

In this case, it is preferable that the parallel link mechanismcomprises six of the rods and controls the position/attitude, in sixdegrees of freedom, of the mask stage by expansion/contraction of eachrod. In such a case, because the position/attitude, in the six degreesof freedom, of the mask stage can be controlled by individualexpansions/contractions of the six rods of the parallel link mechanism,the above Z-tilt mechanism, planar motor, etc., are unnecessary, andtherefore, it is possible to make the mask stage, as the movableportion, more lightweight.

In an exposure apparatus according to the present invention, it ispossible to have the exposure main portion comprise a substrate stage tohold the substrate and a stage base to support the substrate stage insuch a way that the substrate stage is movable, and to make the parallellink mechanism control relative position, in three degrees of freedom,of the first stage base. In such a case, by controlling the relativeposition, in three degrees of freedom, of the first stage base by theparallel link mechanism, the relative position, in three degrees offreedom (e.g. Z, θx, θy), of the substrate stage supported by the firststage base can be controlled. That is, without the Z-tilt mechanismmounted on the substrate stage, it is possible to perform a Z-tilt driveof the substrate, and therefore it is possible to make the substratestage lightweight. In addition, it is possible to reduce driving forceand driving reaction when driving the substrate stage on the first stagebase by, e.g., a planar motor.

In this case, the parallel link mechanism may comprise a first basemember, at least three expandable first rods that link the first basemember and the first stage base, and first expansion mechanisms that arearranged in the respective first rods and expand/contract the respectivefirst rods. In such a case, by individually expanding and contractingthe respective first rods by the first expansion mechanisms that arearranged in the respective first rods, the position/attitude, in atleast three degrees of freedom (e.g. Z, θx, θy), of the first stage baseis controlled. As a result, the position/attitude, in at least threedegrees of freedom, of the substrate stage can be precisely adjustedwith desirable operational-characteristics and high rigidity.

In this case, the first expansion mechanism may comprise an air cylinderand an electromagnetic linear motor that are arranged in parallel or inseries with each other. In such a case, the first stage base can bedriven coarsely and by larger distances by controlling the air pressureof the air cylinder, and also finely by the electromagnetic linearmotor, and as a result, it is possible to precisely control theposition/attitude, in three degrees of freedom (e.g. Z, θx, θy), of thesubstrate stage for a short time.

In this case, in a case where the parallel link mechanism comprises afirst base member, at least three expandable first rods that link thefirst base member and the first stage base, and first expansionmechanisms that are arranged in the respective first rods andexpand/contract the respective first rods, the exposure main portion mayfurther comprise the projection optical system that is supportedindependent from the first stage base and projects the pattern onto thesubstrate.

In such a case, as mentioned above, by individually expanding andcontracting the respective first rods by the first expansion mechanisms,the position/attitude, in at least three degrees of freedom, of thesubstrate stage can be precisely controlled via the first stage basewith desirable operational-characteristics and high rigidity. Therefore,as a result, the adjustment of the relative position, in at least threedegrees of freedom (e.g. Z, θx, θy), between the projection opticalsystem and the substrate, i.e. focus leveling control, can be preciselyperformed with desirable operational-characteristics and high rigidity.By making the substrate stage lightweight, it is possible to reducedriving force and driving reaction when driving the substrate stage onthe first stage base by, e.g., a linear motor, and because theprojection optical system is supported independent from the first stagebase, the reaction to the drive of the substrate stage can be preventedfrom transmitting to the projection optical system. Also, it is easy toseparate the substrate stage and the projection optical system.

In this case, the exposure apparatus may further comprise a positiondetector that is fixed on the projection optical system and detects therelative positional relation, in six degrees of freedom, between thesubstrate and the projection optical system. In such a case, because, asmentioned above, the reaction to the drive of the substrate stage can beprevented from transmitting to the projection optical system, it ispossible to precisely detect the positional relationship, in six degreesof freedom, between the substrate and the projection optical system bythe position detector fixed on the projection optical system.

When its exposure main portion comprises the substrate stage, the firststage base to support the substrate stage, and the projection opticalsystem, an exposure apparatus according to the present invention mayfurther comprise a supporting mechanism that supports the projectionoptical system to be in a fixed state on the floor surface on which theexposure main portion is mounted. In such a case, because thepositions/attitudes, in three degrees of freedom, of the substrate stageis controllable, by initially adjusting the projection optical system totake a desirable position and attitude and having the supportingmechanism support it to be fixed after the initial adjustment, thepositional relationship, in three degrees of freedom, between thesubstrate and the projection optical system can be adjusted.

In an exposure apparatus according to the present invention, theexposure main portion may comprise a mask stage to hold a mask on whichthe pattern is formed and a second stage base to support the mask stageto be movable as well as the substrate stage, the first stage base tosupport this, and the projection optical system, and the parallel linkmechanism may also control the position/attitude, in three degrees offreedom, of the second stage base. In such a case, the reaction to thedrive of the substrate stage can be prevented from transmitting to theprojection optical system, and by the parallel link mechanismcontrolling the position/attitude, in three degrees of freedom, of thesecond stage base, it is possible to precisely adjust the relativeposition and attitude, in three degrees of freedom (e.g. Z, θx, θy),between the mask and the projection optical system with desirableoperational-characteristics and high rigidity. That is, without theZ-tilt mechanism mounted between the mask stage and the second stagebase or on the substrate stage, it is possible to perform afocus-leveling of the mask stage by using the parallel link mechanism,and therefore, the degradation of the pattern image due to the defocusof the mask can be prevented. Especially, when the object side of theprojection optical system is non-telecentric, the positional deviationof the pattern image and the like due to the defocus of the mask can beprevented, too. By making the mask lightweight, it is possible to reducedriving force and driving reaction when driving it on the second stagebase by, e.g., a linear motor and prevent the reaction from transmittingto the projection optical system. Also, it is easy to separate the maskstage and the projection optical system.

In the exposure apparatus according to the present invention, in a casewhere the parallel link mechanism controls the relative position, inthree degrees of freedom, between the mask stage and the projectionoptical system by controlling the position/attitude, in three degrees offreedom, of the second stage base, a position detector that is fixed onthe projection optical system and detects the relative positionalrelation, in six degrees of freedom, between the mask stage and theprojection optical system may be arranged. In such a case, because, asmentioned above, the reactions to the drives of the substrate stage andmask stage are prevented from transmitting to the projection opticalsystem, it is possible to precisely detect the relative positionalrelation, in six degrees of freedom, between the mask stage and theprojection optical system by the position detector fixed on theprojection optical system.

In this case, the position detector may be an interferometer and amirror, for detecting relative position in degrees of freedom X, Y, θz,on which a measurement beam from the interferometer is made incident maybe arranged on the mask stage, and a mirror, for detecting relativeposition in degrees of freedom Z, θx, θy, on which another measurementbeam from the interferometer is made incident may be fixed on the secondstage base.

In this case, in a case where the parallel link mechanism also controlsthe position/attitude, in three degrees of freedom, of the second stagebase, the parallel link mechanism may comprise a second base member, atleast three expandable second rods that link the second base member andthe second stage base, and second expansion mechanisms that are arrangedin the respective second rods and expand/contract the respective secondrods. In such a case, as mentioned above, it is possible to preciselyadjust the relative position between the substrate and the projectionoptical system with desirable operational-characteristics and highrigidity, and the reaction to the drive of the substrate stage can beprevented from transmitting to the projection optical system. Inaddition, by individually expanding and contracting the respectivesecond rods by the second expansion mechanisms that are arranged in therespective second rods, the position/attitude, in at least three degreesof freedom, of the second stage base is controlled. As a result, therelative position, in at least three degrees of freedom (e.g. Z, θx,θy), between the mask and the projection optical system can be preciselyadjusted with desirable operational-characteristics and high rigidity.By making the substrate stage and the mask stage lightweight, it ispossible to reduce driving force and driving reaction and to structurethe substrate stage, the mask stage, and the projection optical systemsuch that they can be easily separated.

In this case, the parallel link mechanism may comprise a third basemember, at least three expandable third rods that link the third basemember and the projection optical system, and third expansion mechanismsthat are arranged in the respective third rods and expand/contract therespective third rods. In such a case, upon the initial adjustment ofthe projection optical system, by individually controlling the expansionmechanisms that are arranged in the respective third rods, the initialadjustment can be easily performed. After the initial adjustment, bykeeping the lengths of the respective third rods by the third expansionmechanisms, the projection optical system can be supported and fixed tobe in a desirable position and attitude. After that, the relativeposition, in at least three degrees of freedom, between each stage andthe projection optical system can be adjusted by controlling theposition/attitude of each stage.

In this case, the third expansion mechanism may comprise an aircylinder. In such a case, the initial adjustment of theposition/attitude of the projection optical system can be easilyperformed by adjusting the inside pressure of the air cylinder.

In an exposure apparatus according to the present invention, the first,second, and third base members, which are respectively connected to thefirst stage base, the second stage base, and the projection opticalsystem respectively via the first, second, and third rods, may each bean individual member, or at least two of the first, second, and thirdbase members may be one common member. That is, the first, second, andthird base members may be one common member, or the first and secondbase members, the second and third base members, or the first and thirdbase members may be one common member.

In an exposure apparatus according to the present invention, at leastone of the first and second expansion mechanisms, which are respectivelyarranged in the first and second rods that respectively link the firstand second stage bases with the first and second base members, maycomprise an air cylinder and an electromagnetic linear motor that arearranged in parallel or in series with each other. In such a case, atleast one of the first and second stage bases can be driven coarsely andby larger distances by controlling the air pressure of the air cylinder,and also finely by the electromagnetic linear motor, and as a result, itis possible to precisely control the position/attitude, in three degreesof freedom (e.g. Z, θx, θy), of at least one of the substrate stage andmask stage, and then precisely adjust the relative position andattitude, in three degrees of freedom (e.g. Z, θx, θy), of at least oneof the substrate and mask with respect to the projection optical system,for a short time. That adjustment is a so-called focus-leveling.

In this case, it is preferable that at least one of the first and secondrods further comprises a bearing unit that supports the mover of theelectromagnetic linear motor with respect to its stator in non-contactmanner. In such a case, because friction that works as a non-linearcomponent upon controlling the expansion/contraction of the rod havingthe bearing unit by the expansion mechanism can be avoided, theposition/attitude, in three degrees of freedom, of at least one of thewafer stage and the mask stage can be more precisely controlled via atleast one of the first and second stage bases.

Note that in this case, either of a gas static pressure bearing unit anda magnetic bearing unit can be used as the bearing unit.

When a gas static pressure bearing unit is used as the bearing unit, itis preferable that a differential exhaust mechanism is arranged in itsneighbor so that a gas supplied to the gas static pressure bearing unitdoes not contaminate the gas purity of the atmosphere inside theexposure apparatus.

In an exposure apparatus according to the present invention, therelative position between at least one of both the stages and theprojection optical system may be statically adjusted by using the aircylinder, and also a controller to suppress vibrations by using theelectromagnetic linear motor may be provided. In such a case, it ispossible to adjust the relative position between at least one of boththe stages and the projection optical system via at least one of thefirst and second stage bases and suppress vibrations due toexpansion/contraction of each rod.

An exposure apparatus according to the present invention may furthercomprise a controller that insulates high-frequency vibrations bycontrolling the current of the electromagnetic linear motor whilelow-frequency vibrations are suppressed by the control of the airpressure of the air cylinder. In such a case, low-frequency vibrationsgenerated in each stage base due to the reaction to its drive aresuppressed, and besides, fine vibrations from the floor surface,high-frequency vibrations, can be insulated.

In an exposure apparatus according to the present invention, a pluralityof stages may be mounted on at least one of the first and second stagebases. For example, in a case where a plurality of stages, i.e.substrate stages, are mounted on the first stage base, because exchangeof substrates, detection of alignment marks of a substrate, or the likeon another substrate stage can be performed during exposure for asubstrate on one substrate stage, the throughput can be improvedcompared with the case of a single substrate stage. Furthermore, forexample, in a case where a plurality of stages, i.e. mask stages, aremounted on the second stage base, because the exchange of masks isperformed by exchanging the positions of the mask stages, it is possibleto perform multi-exposure such as double exposure using a plurality ofmasks with a higher throughput. Especially, in a case where a pluralityof the substrate stages and mask stages are provided, because exchangeof substrates, detection of alignment marks of a substrate or the likeon another substrate stage can be performed during multi-exposure for asubstrate on one substrate stage, multi-exposure such as double exposureusing a plurality of masks can be performed with a higher throughput.

In an exposure apparatus according to the present invention, theexposure main portion may comprise a mask stage to hold the mask onwhich the pattern is formed and a stage base to support the mask stagein such a way that the mask stage is movable, and the parallel linkmechanism may control the position/attitude, in three degrees offreedom, of the stage base. In such a case, by the parallel linkmechanism controlling the position/attitude, in three degrees offreedom, of the stage base, the position/attitude, in three degrees offreedom, of the mask can be precisely adjusted with desirableoperational-characteristics and high rigidity. By making the mask stagelightweight, it is possible to reduce driving force and driving reactionwhen driving it on the stage base by, e.g., a linear motor.

In this case, the parallel link mechanism may comprise a base member, atleast three expandable rods that link the base member and the stagebase, and expansion mechanisms that are arranged in the respective rodsand expand/contract the respective rods. In such a case, it is possibleto precisely adjust the relative position, in at least three degrees offreedom (e.g. Z, θx, θy), of the mask stage with desirableoperational-characteristics and high rigidity by individually expandingand contracting the respective rods by the expansion mechanisms that arearranged in the respective rods and controlling the position/attitude,in at least three degrees of freedom, of the stage base. Also, by makingthe mask stage lightweight, it is possible to reduce driving force anddriving reaction of each stage.

An exposure apparatus according to the present invention may comprise achamber to contain at least one part of the exposure main portion in astate where it is sealed from the outside atmosphere and its attitude isallowed to change. In such a case, it is possible to make a part of theexposure main portion, which is supported by the parallel linkmechanism, lightweight by using the advantages of the parallel linkmechanism, and its attitude can be precisely controlled with desirableoperational-characteristics and high rigidity. Furthermore, because thechamber contains at least one part of the exposure main portion in astate where it is sealed from the outside atmosphere and its attitude isallowed to change, by filling the chamber with nitrogen gas (N₂), heliumgas (He) or the like it is possible to transfer a fine pattern onto asubstrate with high resolution using ArF excimer laser light or vacuumultraviolet light such as F₂ laser light, whose wavelength is shorterthan ArF light.

In this case, it is preferable that a vacuum exhaust system and a gassupply system to purge non-active gas into the chamber are arranged inthe exposure apparatus. In such a case, by having a gas inside thechamber exhausted by a vacuum exhaust system and having a non-active gassuch as nitrogen gas (N₂) and helium gas (He) supplied by a gas supplysystem, the gas inside the chamber is replaced by the non-active gas atonce and the inside pressure is set to be at a desirable value.

In a case where the exposure main portion comprises the substrate stageand the first stage base to support it, the projection optical system,the mask stage and the second stage to support it, and the parallel linkmechanism to adjust the positions/attitudes, in three degrees offreedom, of the first and second stage bases, an exposure apparatusaccording to the present invention may further comprise a chamber thatcomprises a first room to contain the mask stage and include the secondstage base as a part, a second room to contain the projection opticalsystem, a third room to contain the substrate stag and include the firststage base as a part, and expandable, bellows-members, whichrespectively link the first room and the second room, and the secondroom and the third room, and seals the substrate stage, the opticalprojection system, and the mask stage from the outside atmosphere. Insuch a case, the third room, which includes the first stage base as apart, contains the substrate stag; a second room contains the projectionoptical system; a first room, which includes the second stage base as apart, contains the mask stage; and expandable, bellows-members link thefirst room, the second room, and the third room. Therefore, it ispossible to adjust the positions/attitudes, in three degrees of freedom,of the first and second stage bases by the parallel link mechanismwithout any problem. Also, the substrate stage, the optical projectionsystem, and the mask stage are sealed from the outside atmosphere.Therefore, by filling the inside of the chamber with nitrogen gas (N₂),helium gas (He) or the like, it is possible to transfer a fine patternonto a substrate with high resolution using ArF excimer laser light orvacuum ultraviolet light such as F₂ laser light, whose wavelength isshorter than ArF light.

In this case, it is preferable that a vacuum exhaust system and a gassupply system to purge non-active gas into the chamber are arranged inthe exposure apparatus. In such a case, by having a gas inside thechamber exhausted by a vacuum exhaust system and having a non-active gassuch as nitrogen gas (N₂) and helium gas (He) supplied by a gas supplysystem, the gas inside the chamber is replaced by the non-active gas atonce and the inside pressure is set to be at a desirable value.

According to the third aspect of the present invention, there isprovided a first method of making an exposure apparatus to transfer apattern of a mask onto a substrate, comprising a first step of providingan mask stage to hold the mask; a second step of providing an opticalprojection system to transfer a pattern of the mask onto a substrate; athird step of providing a substrate stage to hold the substrate; and afourth step of providing a parallel link mechanism to support at leastone of the mask stage and the substrate stage in such a way thatrelative position, at least three degrees of freedom, of at least one ofthe mask stage and the substrate stage with respect to the opticalprojection system.

According to this, by assembling and adjusting the illumination opticalsystem, the projection optical system, the mask stage and substratestage, the parallel link mechanism to support at least one of the maskstage and the substrate stage in such a way that relative position, atleast three degrees of freedom, of at least one of the mask stage andthe substrate stage with respect to the optical projection system arecontrollable, and other various elements mechanically, optically, andelectrically, an exposure apparatus according to the present inventioncan be made.

According to the fourth aspect of the present invention, there isprovided a second method of making an exposure apparatus to transfer apattern of a mask onto a substrate, comprising a first step of providingan mask stage to hold the mask; a second step of providing an opticalprojection system to transfer a pattern of the mask onto a substrate; athird step of providing a substrate stage to hold the substrate; afourth step of providing a first stage base to support the mask stage tobe movable; a fifth step of providing a second stage base to support thesubstrate stage to be movable; and a sixth step of providing a parallellink mechanism to support at least one of the first and second stagebases in such a way that relative position, at least three degrees offreedom, of at least one of the first and second stage bases withrespect to the optical projection system is controllable.

According to this, by assembling and adjusting the illumination opticalsystem, the projection optical system, the mask stage and substratestage, the first stage base to support the substrate stage to bemovable, the second stage base to support the mask stage to be movable,the parallel link mechanism to support at least one of the first andsecond stage bases in such a way that relative position, at least threedegrees of freedom, of at least one of the first and second stage baseswith respect to the optical projection system is controllable, and othervarious elements mechanically, optically, and electrically, an exposureapparatus according to the present invention can be made.

In addition, in the lithography process, by performing exposure using anexposure apparatus according to the present invention, it is possible toform a multi-layer pattern on the substrate with high precision ofsuperposition, and therefore it is possible to manufacture a more highlyintegrated micro device with high yield. Therefore, another aspect ofthe present invention is a method of manufacturing a device using anexposure apparatus according to the present invention.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic view showing the arrangement of an exposureapparatus according to the first embodiment;

FIG. 2 is a planar view showing the structure, some parts of which arenot shown, of the parallel link mechanism of FIG. 1;

FIG. 3 is a cross-sectional view showing the first rod 78, of FIG. 1,some part of which is not shown;

FIG. 4 is a schematic view showing the structural model of a drivingsystem so as to explain the principle of the control of a parallel linkmechanism in an exposure apparatus according to the first embodiment;

FIG. 5 is a block diagram showing a control model for the driving systemof FIG. 4;

FIG. 6 is a view showing a relation between a stationary coordinate anda rod coordinate;

FIG. 7 is a view for explaining the rod's structural model of FIG. 4 andreactions exerted on the rod and a driven body;

FIG. 8 is a block diagram showing the structure of a control system ofan exposure apparatus according to the first embodiment;

FIG. 9 is a schematic view showing the structure of an exposureapparatus according to the second embodiment;

FIG. 10 is an oblique view showing the first parallel link mechanism ofFIG. 9;

FIG. 11 is a planar view showing a wafer laser interferometer system todetect the position, in X-Y plane, of the wafer stage of FIG. 9;

FIG. 12 is a schematic view showing the structural model of a drivingsystem so as to explain the principle of the control of a parallel linkmechanism in an exposure apparatus according to the second embodiment;

FIG. 13 is a view showing a state that the wafer stage is driven inX-axis direction by the first parallel link mechanism;

FIG. 14 is a view showing a state that the wafer stage is driven inZ-axis direction by the first parallel link mechanism;

FIG. 15 is a view showing a state that the rolling of the wafer stage iscontrolled by the first parallel link mechanism;

FIG. 16 is a view showing a state that the yawing of the wafer stage iscontrolled by the first parallel link mechanism;

FIG. 17 is a block diagram showing the structure of a control system ofan exposure apparatus according to the second embodiment;

FIG. 18 is a flow chart for explaining a method of manufacturing adevice using an exposure apparatus according to the present invention;

FIG. 19 is a flow chart showing the process of the wafer process step(step 204) of FIG. 18;

BEST MODE FOR CARRYING OUT THE INVENTION A First Embodiment

A first embodiment of the present invention will be described below withreferring to FIGS. 1 to 8.

FIG. 1 shows the schematic arrangement of an exposure apparatus 10according to an embodiment. The exposure apparatus 10 is a so-calledstep-and-scan type scanning exposure apparatus that while illuminatingthe reticle R as a mask with exposure illumination light EL that isvacuum-ultraviolet, synchronously moves reticle R and wafer W as asubstrate in a scanning direction (hereafter, defined to be Y-directionthat is the lateral direction in FIG. 1) and transfers a pattern on thereticle R onto a plurality of shot areas on the wafer W through aprojection optical system PL. This exposure apparatus 10 is a so-calledscanning stepper.

This exposure apparatus 10 includes an illumination optical system IOPthat illuminates the reticle R with the exposure illumination light ELfrom a light source (not shown), a reticle stage RST serving as a maskstage for holding the reticle, a projection optical system PL forprojecting the exposure illumination light EL sent out from the reticleR onto a wafer W, and a wafer stage WST serving as a substrate stage forholding and moving the wafer W in X-Y two dimensional direction.

The above illumination optical system IOP is supported by anillumination-system supporting member (not shown). This illuminationoptical system IOP includes an illumination-system housing that makesthe inside airtight from the atmosphere and is filled with alow-absorbing gas, which is so clean and non-active as to include a fewor less than a few percent concentration of air (oxygen), or desirablyless than one percent, and low in the absorption of light having thewavelength of vacuum ultraviolet, such as dry nitrogen (N₂), helium(He), argon (Ar), neon (Ne), and krypton (Kr) or a gas in which thosegases are mixed. This is because, in the case of using light having thewavelength of vacuum ultraviolet as exposure illumination light, a gas(hereafter, referred to as an “absorptive gas” as the need arises) suchas oxygen, steam, and hydrocarbon or related gas, which greatly absorbslight having such a wavelength, has to be removed from the optical path.The inside of the illumination system housing is filled with thenon-active gas mentioned above (hereafter, referred to as a “lowabsorptive gas” as the need arises) and kept to have a one to tenpercent higher pressure than the air.

The illumination system housing houses, as disclosed in, for example,Japanese Patent Laid-Open No. 7-142354 and U.S. Pat. No. 5,534,970corresponding thereto, etc., a beam reshaping system, a fly-eye lens asan optical integrator, a vibration mirror, a collective lens system, arelay lens, a reticle blind mechanism, a main condenser-lens system,etc. in a predetermined arrangement. The above disclosures areincorporated herein by this reference as long as the national laws indesignated states or elected states, to which this internationalapplication is applied, permit.

At the backside of the FIG. 1 of the illumination optical system IOP, afret optical system including an optical system for optical axisadjustment that is called a beam matching unit is connected with atleast one portion of the illumination optical system IOP, and via thefret optical system a light source (not shown) arranged on a floorsurface FD is connected. As this light source, for example, a lightsource to emit light, of which the wavelength is in the rang of about120 nm to about 180 nm and belongs to vacuum ultraviolet region, such asfluorine laser of 157 nm as the oscillation wavelength (F₂ laser),krypton dimer laser of 146 nm (Kr₂ laser) and argon dimer laser of 126nm (Ar₂ laser) is employed. Note that ArF excimer laser, etc., can alsobe used as the light source. A light source controller (not shown) isconnected with this light source and controls the oscillation centerwavelength of a pulse ultraviolet light emitted from the source, thetrigger of the pulse oscillation, a gas inside the laser chamber, etc.

A slit-like illumination area on the reticle R that is defined by afixed reticle blind (fixed field stop) is illuminated with uniformilluminance by the illumination optical system IOP. In this case, theslit-like illumination area is set to be in the center of a circularprojection field of the projection optical system PL shown in FIG. 1 andextend in the X-direction (non-scanning direction) with the width inY-direction (scanning direction) being almost constant.

Incidentally, this light source could be installed in a utility spaceprovided on the floor of a room (service room), having lower cleannessthan a clean room, or the clean room.

The above reticle stage RST is levitated above the upper surface of areticle base level block 12, having a triangle shape in a planar viewand serving as a second stage-base, with a predetermined clearance, forexample, of about 5 um via a non-contact bearing (not shown; for examplean air-pad). This reticle stage RST is scanned in the Y-direction, thescanning direction, within a predetermined stroke range and can befinely moved on a horizontal plane (X-Y plane) by a reticle driver 14(not shown in FIG. 1; refer to FIG. 8) including a linear motor, etc.The reticle R is fixed on this reticle stage RST by vacuum chucking orelectrostatic chucking.

On the upper surface of the reticle base level block 12, a bulkhead 16having a rectangular opening 16 a, which is reduced in size from thereticle R, formed thereon is provided. And this bulkhead 16 and thereticle stage base 12 compose a reticle room 18 as a first room to housethe reticle stage. The bulkhead 16 is made of a material, which does notemit a large amount of gas, such as stainless (SUS). The upper end ofthe bulkhead 16 is connected to the emitting end of the illuminationsystem housing by bellows-like member 20 such that its inside is sealedfrom the outside air, the member 20 being expandable and being made offluorine rubber that is a chemically clean material.

On the emitting end of the illumination system housing, a transmissionwindow (not shown) is arranged such that it seals the inside space ofthe illumination system housing from that of the reticle room 18. Thistransmission window is arranged in the optical path of exposureillumination light EL that is incident on reticle R from theillumination optical system IOP, thereby being made of a crystalmaterial, which has high transmittance against vacuum ultraviolet asexposure illumination light, such as fluorite.

On the reticle base level block 12, a rectangular opening, in thecross-sectional view, that is the path of the exposure illuminationlight EL having passed the reticle R is formed. On the reticle baselevel block 12, an opening 12 a, which is vertically penetrating and hasa supporting member for a reticle laser interferometer (described later)inserted therein, is also formed. Incidentally, the supporting mechanismand the like of the reticle base level block 12 will be described later.

The position of the reticle stage RST in the X-Y plane (X position, Yposition, and rotation around Z-axis (θz rotation)) is measured with apredetermined resolution, for example about 0.5 to 1 nm, via a movablemirror 22R fixed on the reticle stage RST by the reticle laserinterferometer 24R. In practice, on the reticle stage RST, aX-movable-mirror having a reflection surface perpendicular to theX-direction and a Y-movable-mirror having a reflection surfaceperpendicular to the Y-direction are arranged, and two reticleinterferometers 24Ry₁, 24Ry₂ for measuring the position in theY-direction and a interferometer 24Rx for measuring the position in theX-direction are arranged (refer to FIG. 8). In FIG. 1, those arerepresentatively shown by the movable mirror 22R and the reticle laserinterferometer 24R.

The bottom ends of the reticle laser interferometer 24R, that is,interferometers 24Ry₁, 24Ry₂, 24Rx are fixed on the upper portion of thelens-barrel of the projection optical system PL, and the upper ends ofthose are respectively fixed via the opening 12 a and similar openings(not shown) to the upper ends of three supporting members 26 that areexposed on the reticle base level block 12.

The measurement values of the reticle laser interferometer 24R, that is,interferometers 24Ry₁, 24Ry₂, 24Rx are supplied to the stage controller52 and then to the main controller 50 (refer to FIG. 8). In the stagecontroller 52, according to the average of the measurement values of theinterferometers 24Ry₁, 24Ry₂ the Y position of the reticle stage RST iscalculated, according to the difference of those measurement values andthe distances between the axes of the interferometers the θz rotation iscalculated, and according to the average of the measurement values ofthe interferometers 24Rx the X position of the reticle stage RST iscalculated. The stage controller 52 reports those results of thecalculations to the main controller 50 in real time.

Furthermore, a reflection mirror 28 is fixed to the bottom surface ofthe reticle base level block 12 and a reticle base interferometer 30 tomeasure the Z position of the reflection mirror 28 is disposed on apredetermined position around the periphery of the upper end of theprojection optical system PL. Incidentally, in practice, on the bottomsurface of the reticle base level block 12, reflection mirrors are fixedto three different position, and a first interferometer 30 ₁, a secondinterferometer 30 ₂, and a third interferometer 30 ₃ are respectivelyarranged on three positions around the periphery of the upper end of theprojection optical system corresponding to the three mirrors (refer toFIG. 8). In FIG. 1, those are representatively shown by a reflectionmirror 28 and a reticle base interferometer 30. The first interferometer30 ₁, the second interferometer 30 ₂, and the third interferometer 30 ₃respectively measure the Z positions of three reflection mirrors. Themeasurement values of these three interferometer 30 ₁, 30 ₂, and 30 ₃are supplied to the stage controller 52 and then the main controller.The stage controller 52 calculates the Z position, θx rotation(pitching), and θy rotation (rolling) by performing a predeterminedcomputing on the basis of the measurement values of the threeinterferometer 30 ₁, 30 ₂, and 30 ₃. These results are reported from thestage controller 52 to the main control 50 in real time.

In the projection optical system PL, an optical system comprising a lensand a reflection mirror made of fluoride crystal such as fluorite andlithium fluoride is supported by the lens-barrel. In this embodiment, asthis projection optical system PL, a reduction system is employed whichhas, for example, a circular image field and of which the object planeside and image plane side are both telecentric and the reductionmagnification β is, e.g. ¼ or ⅕. As this projection optical system,although a refraction optical system may be used which is composed ofonly lenses made of fluoride crystal, in this embodiment areflection/refraction-type projection optical system (catadioptricsystem) is employed. By using an scanning exposure apparatus comprisingsuch a reflection/refraction-type projection optical system, it ispossible to precisely transfer a fine pattern of about 100 nm L/Spattern onto wafers even with F₂ laser light having, for example, thewavelength of 157 nm as exposure light. Note that an optical systemcomposed of only reflection optical elements may be used as theprojection optical system.

As the reflection/refraction-type projection optical system, areflection/refraction system comprising a beam splitter and a concavemirror as reflection optical elements, which is disclosed in, forexample, Japanese Patent Laid-Open No. 8-171054 and U.S. Pat. No.5,668,672 corresponding thereto, and Japanese Patent Laid-Open No.10-20195 and U.S. Pat. No. 5,835,275 corresponding thereto, can be used,or a reflection/refraction system comprising not a beam splitter but aconcave mirror, etc., as reflection optical elements, which is disclosedin Japanese Patent Laid-Open No. 8-334695 and U.S. Pat. No. 5,689,377corresponding thereto, and Japanese Patent Laid-Open No. 10-3039 andU.S. Pat. No. 873,605 (application date: Jun. 12, 1997) correspondingthereto, can be employed. The disclosures in the above Japanese PatentLaid-Opens, U.S. patent, and U.S. patent application are incorporatedherein by this reference as long as the national laws in designatedstates or elected states, to which this international application isapplied, permit.

As the reflection/refraction-type projection optical system, also areflection/refraction system can be employed which comprises a pluralityof refraction optical elements and two mirrors (a main mirror being aconcave mirror and a sub-mirror that is a back surface mirror of whichthe reflection surface is formed on the opposite side to the incidentsurface of a refraction element or plane parallel plate) that aredisposed along one axis and has the intermediate image of a reticlepattern again imaged on a wafer using the main mirror and sub-mirror,and is disclosed in Japanese Patent Laid-Open No. 10-104513 and U.S.Pat. No. 5,488,229 corresponding thereto. In this reflection/refractionsystem, the main mirror and sub-mirror are disposed in series with theplurality of refraction optical elements, and an illumination lightpasses through a portion of the main mirror, is reflected by thesub-mirror and the main mirror in turn, passes through a portion of thesub-mirror and reaches the wafer. The disclosures in the above JapanesePatent Laid-Opens and U.S. patent are incorporated herein by thisreference as long as the national laws in designated states or electedstates, to which this international application is applied, permit.

In this embodiment, as described above, as a projection optical system,because the reduction optical system of the reduction magnification β,e.g. ¼ or ⅕, is employed, when the reticle R is illuminated with theexposure illumination light EL from the illumination optical system IOP,the reduced image (partially inverted image) of a circuit pattern in theslit-like illumination area on the reticle is formed on the exposurearea, conjugate with the slit-like illumination area, on the wafer.

Like the present embodiment, in a exposure apparatus using a exposurewavelength of vacuum ultraviolet, also a gas inside the lens-barrel ofthe projection optical system PL has to be replaced by the abovenon-active gas (low absorptive gas) to avoid the absorption of theexposure illumination light by a absorptive gas such as oxygen.Therefore, in the present embodiment, the inside of the lens-barrel ofthe projection optical system PL is filled with the above non-activegas, and the pressure of the inside is set to be at the predeterminedvalue. The method in which the gas inside the lens-barrel of thisprojection optical system PL is replaced with the above non-active gaswill be described later.

On a position somewhat below the center, in the vertical direction, ofthe lens-barrel of the projection optical system PL, a flange FLG isprovided. The whole lens-barrel including the flange FLG is covered by abulkhead made of a material, which does not emit a large amount of gas,such as stainless (SUS), and a lens room 32 serving as a second room toaccommodate the projection optical system PL is formed by this bulkhead.In a portion of the ceiling of the bulkhead forming the lens room 32, anopening is formed, and the outside of the opening is connected to thereticle base level block 12 through an expandable bellows-like member34, which is made of fluorine-contained rubber, in the state where theinside is sealed from the atmosphere. Moreover, in the bottom wall ofthe bulkhead forming the lens room 32, an opening, which is the path forthe exposure illumination light EL projected from the projection opticalsystem PL to the wafer W, is formed. The outside of the opening isconnected to a bulkhead forming a wafer room (described later) throughan expandable bellows-like member 36, which is made offluorine-contained rubber, in the state where the inside is sealed fromthe atmosphere.

On a wafer base level block 38 that is triangle, in a planar view, andserves as a first stage base, the above wafer stage WST is freely drivenin the X-Y plane by a wafer driver 40 (not shown in FIG. 1; refer toFIG. 8) composed of a magnetic-levitation-type two-dimensional linearactuator (planar motor) that is disclosed in, for example, U.S. Pat. No.519,745, etc. The disclosure in the above U.S. patent is incorporatedherein by this reference as long as the national laws in designatedstates or elected states, to which this international application isapplied, permit.

The wafer W is fixed on this wafer stage WST by vacuum chucking orelectrostatic chucking (both are not shown).

A bulkhead 42 on which an opening of a predetermined shape is formed isarranged on the wafer base level block 38 and a wafer room 44 serving asa third room to accommodate the wafer stage WST is formed by thebulkhead 42 and the wafer base level block 38. The bulkhead 42 is madeof a material, which does not emit a large amount of gas, such asstainless (SUS). Furthermore, as described above, the upper end of thebulkhead 42 is connected to the bottom end of the lens room 32 a throughthe expandable bellows-like member 36 in the state where the inside issealed from the atmosphere. The supporting mechanism, etc., of the waferbase level block will be described later.

In the present embodiment, a chamber 46 isolating the wafer stage WST,the projection optical system PL, and the reticle stage RST from theatmosphere is composed of the reticle base level block 12 and thebulkhead 18 that compose the reticle room 18, a bulkhead composing thelens room 32, the wafer base level block 38 and the bulkhead 42 thatcompose the wafer room 44, the bellows-like member 36 connecting thelens room 32 and the reticle room 18, and the bellows-like member 20connecting the reticle room 18 and the illumination optical system IOP(refer to FIG. 1). Like the present embodiment, in the case of employinglight having a wavelength in ultraviolet region as the exposureillumination light, the above absorptive gas such as oxygen has to beremoved from the optical path. Therefore, the inside of the chamber 46,that is, the reticle room 18, the lens room 32, and the wafer room 44 isfilled with a low absorptive gas, for example helium, to set the insidepressure at a predetermined value.

This will be elaborated below. One end of a first pipe 48 made of aflexible tube is connected to the bulkhead 16 of the reticle room 18composing the chamber 46 and the other end of the first pipe 48 isconnected to the discharge opening of a helium gas supplier (hereafter,referred to as a “gas supplier”) 54, and the one end of a second pipe 56made of a flexible tube is connected to the bulkhead of the wafer room44 composing the chamber 46, and the other end of the second pipe 56 isconnected to the inflow opening of a channel switching unit 58comprising the channel switching valve (three way valve) composed of anelectromagnetic valve. The first outflow opening of this channelswitching unit 58 is connected with the return opening of the gassupplier 54 via a third pipe 60. Furthermore, the second outflow openingof this channel switching unit 58 is connected with a turbo molecularpump 66 and then a dry pump 68 via pipes 62, 64.

The above gas supplier 54 has a gas container containing helium gas thatis so clean as to contain less than one percent concentration of oxygen.First and second pumps are provided respectively on the dischargeopening side (exit side) and return opening side (entrance side) of thegas container. A temperature adjustment unit (not shown) controls thehelium gas inside the gas container to be kept at a predetermined targettemperature. Moreover, a chemical filter, air filter, etc., are arrangedaround the return opening.

The method of replacing the gas (air) inside the chamber 46 with heliumwill be briefly described below. Note that the operation described belowis performed while the main controller 50 (refer to FIG. 8) describedlater is monitoring the output, etc., of a pressure sensor (not shown).

First, the channel switching valve inside the channel switching unit 58is switched to the side of the turbo molecular pump 66, and then the drypump 68 is turned on to vacuum the inside of the chamber 46. Next, afterthe inside of the chamber gets to be at a predetermined first vacuumstate, the turbo molecular pump 66 is turned on and simultaneously thedry pump 68 is turned off to further vacuum the inside of the chamber46. After the inside of the chamber 46 gets to be at a predeterminedsecond vacuum state of, e.g., less than 0.1 hPa, the channel switchingvalve inside the channel switching unit 58 is switched to the side ofthe gas supplier 54 and simultaneously the turbo molecular pump 66 isturned off. By the above lowering of the pressure, the absorptive gassuch as oxygen is removed from the inside of the chamber 46.

Next, a charging valve (not shown) in the gas supplier is opened andsimultaneously the first pump is turned on to start the supply of heliumgas from the gas supplier 54 to the chamber 46. Then after the pressureinside the chamber 46 reaches the predetermined value after apredetermined time since the start of the supply, the charging valve isclosed and simultaneously the first valve is turned off.

In such a way, the replacement of gases inside the chamber 46 isperformed, and the inside of the chamber 46, more specifically, thereticle room 18, the lens room 32, the wafer room 44, and the inside ofthe lens-barrel of the projection optical system PL is filled withhelium.

Note that in the present embodiment, as is obvious seeing FIG. 1, thesupply system of helium gas is a circulation system having thecirculating path for helium gas and is economical. In this case, thereis a high possibility of helium gas, which returns to the returningopening of the gas supplier 54, containing particles or chemicalimpurities, but as described above, the chemical filter, air filter,etc., arranged around the returning opening remove them, and highlyclean helium gas, which is chemically clean and has almost no particles,returns to the inside of the gas container.

The position of the wafer stage WST in the X-Y plane (X position, Yposition, and θz rotation) is measured with a predetermined resolution,for example about 0.5 to 1 nm, via a movable mirror 22W fixed on thewafer stage WST by the wafer laser interferometer 24W that is suspendedfrom and supported by a supporting member 70 below the lens-barrel ofthe projection optical system PL.

Incidentally, a reflection surface may be formed on a predeterminedportion of the upper surface of the wafer base level block 38 byperforming mirror-process and a wafer base interferometer for measuringthe Z position of the reflection surface may be fixed on the lower sideof the wafer laser interferometer 24W.

In this case, in practice, on the wafer stage WST, a X movable mirrorhaving a reflection surface perpendicular to the X-axis and a Y movablemirror having a reflection surface perpendicular to the Y-axis arearranged, and two wafer interferometers 24Wy₁, 24Wy₂ for measuring theposition in the Y-direction and a interferometer 24Wx for measuring theposition in the X-direction are arranged (refer to FIG. 8). Themeasurement values of the wafer laser interferometer 24W, that is,interferometers 24Wy₁, 24Wy₂, 24Wx are supplied to the stage controller52 and then to the main control 50 (refer to FIG. 8). In the stagecontroller 52, according to the average of the measurement values of theinterferometers 24Wy₁, 24Wy₂ the Y position of the wafer stage WST iscalculated; according to the difference of those measurement values andthe distances between the axes of the interferometers the θz rotation iscalculated; and according to the average of the measurement values ofthe interferometers 24Wx the X position of the wafer stage WST iscalculated. The stage controller 52 reports those results of thecalculations to the main controller 50 in real time.

Meanwhile, the z direction position of the wafer with respect to theprojection optical system as a reference is measured by a focus sensor73 that is fixed on the lens-barrel of the projection optical system PLand uses an oblique incident-light method. This focus sensor 73 is, asshown in FIG. 1, composed of a sending light system 73 a, which is fixedon the periphery of the lens-barrel of the projection optical system andilluminates the surface of the wafer W with a detection beam in aoblique direction, and a receiving light system 73 b, which is fixed onthe periphery of the lens-barrel of the projection optical system andreceives the detection beam reflected by the surface of the wafer W. Inthis case, the sending light system 73 a and the receiving light system73 b are both so disposed that they form an angle of 45 degrees withrespect to the X-axis and Y-axis. As this focus sensor, a multiple focalposition detection system is employed which is disclosed in, forexample, Japanese Patent Laid-Open No. 6-283403 and its correspondingU.S. Pat. No. 5,448,332. The disclosures in the above Japanese PatentLaid-Opens and U.S. patent are incorporated herein by this reference aslong as the national laws in designated states or elected states, towhich this international application is applied, permit. Note that thisfocus sensor 73 (73 a, 73 b) are integrally fixed on the projectionoptical system PL.

The output of this focus sensor 73 is supplied to the stage controller52 and the stage controller 52 calculates the relative position, in Z,θx, and θy directions, of the wafer W with respect to the projectionoptical system, more specifically, the z position (the amount ofdefocus), and θx rotation (the amount of pitching) and θy rotation (theamount of rolling) of a target in the exposure area of the wafer'ssurface on the basis of the output of this focus sensor 73. Thesecalculation results, which are focus-leveling measurement results of thetarget in the wafer W's exposure area are reported from the stagecontroller 52 to the main control 50 in real time.

Next, the respective supporting mechanisms of the above reticle baselevel block 12, the projection optical system PL, and the wafer baselevel block 38 will be described below. As this supporting mechanism, inthe present embodiment, a parallel link mechanism 74 is employed. FIG. 2is a planar view that shows some of its elements composing the parallellink mechanism 74. Incidentally, FIG. 1 is a cross-sectional view alongA—A line in FIG. 2.

The parallel link mechanism 74 comprises a first mechanism that controlsthe position and attitude, in three degrees of freedom Z, θx, θy, of thewafer base level block 38, a second mechanism that controls the positionand attitude, in three degrees of freedom Z, θx, θy, of the reticle baselevel block 12, and a third mechanism that controls the position andattitude, in three degrees of freedom Z, θx, θy, of the projectionoptical system PL.

Out of these mechanisms, the first mechanism has three first basemembers 761, 762, 763 (refer to FIG. 2) placed around respectivevertices of an equilateral triangle and three expandable first rods 781,782, 783 that respectively link the first base members 761, 762, 763with the wafer base level block 38.

These first rods 781, 782, 783, as shown in FIG. 1, each have a firstaxis member 79 and a second axis member 80 that can relatively movealong their axis-direction, and the one end (lower end) of the firstaxis member 79 is attached to the corresponding first base member 76 soas to be rotatable around a supporting spindle 81 composed of a bolt orpin, and then the other end (upper end) of the second axis member 80 isattached to the wafer bas level block 38 so as to be rotatable in thesame way as the above.

FIG. 3 shows the cross section (partially omitted) of the first rod 781.As shown in FIG. 3, inside the first axis member 79, a cavity 82 that isshaped like a cylinder with steps is formed, and in one end (left sidein FIG. 1) of the inside of this cavity 82 a bellows-type air cylinder84 is contained. This air cylinder 84 has an end of a pipe 86, which isone portion of an air pressure circuit (not shown), connected thereto,and the other end of a pipe 86 is connected to an air pressure source.And by controlling the air pressure of compressed air supplied from theair pressure source via the air pressure circuit, the inside pressure ofthe air cylinder 84 is controlled. By this, a piston 84A is moved backand forth along the axis direction. In the air cylinder 84 in FIG. 3,the return process uses the gravity exerted on the piston 84A in thestate of being embedded in the parallel link mechanism 84.

Moreover, on the other end inside the cavity 82 of the first axis member79, an armature unit 88 composing the stator in a shaft motor 92, whichis a kind of electromagnetic force linear motor and composed of aplurality of armature coils arranged in the axis-direction, is disposed.As the shaft motor 92, a three-phase motor is employed. Therefore, thearmature unit 88 is constituted of a plurality of coil units connectedin series each of which has three coils connected in series each ofwhich is for one phase and has a coil-axis-direction length of L/3, athird of a pitch L (described later).

Meanwhile, the second axis member 80 has a tube-like mover-yoke 80 a,which is composed of magnetic members, and an attachment member 80 bprovided on the other end (right end in FIG. 3), in the axis-direction(longitudinal direction), of this mover-yoke 80 a. On the periphery ofthe mover-yoke 80 a, a hollow, columnar, that is cylindrical, magneticbody 89 composed of a plurality of permanent magnets having the samesize as one another is arranged. In this case, a hollow, columnarmagnetic pole unit 90 as a mover of the shaft motor 92 is composed ofthe mover-yoke 80 a and the magnetic body 89. The magnetic body 89comprises a plurality of first-magnets, which are arranged at apredetermined distance along the axis-direction and each are acylindrical permanent magnet magnetized in the axis-direction, and aplurality of second-magnets each of which is arranged between theneighboring two first-magnets and is a permanent magnet magnetized inthe radius direction. Two poles of mutually neighboring twofirst-magnets, which are opposite with each other, have the samepolarity as each other. Also, second-magnets are so arranged that theirmagnetization directions are alternatively opposite and that their poleshaving the same polarity as their neighboring first-magnets' poles arefacing outwards.

Therefore, in the neighbor of the stator, an open magnetic circuit (orclose magnetic circuit) having a pitch (L) of 2L1 is formed omnidirectionally (radially) as the length of the first-magnet andsecond-magnet is represented by L1.

In the shaft motor 92 composed in this way, when supplying a drivingcurrent of sine wave having a predetermined period and amplitude to eachcoil of the armature unit 88 as the stator, the second axis member 80 isrelatively driven in the axis-direction with respect to the first axismember 79 by Lorentz force (thrust), a kind of electromagnetic reaction,between the magnetic pole unit 90 and the armature unit 88.

That is, in the present embodiment, the above air cylinder 84 and shaftmotor 92 relatively drive the first axis member 79 and the second axismember 80 in the axis-direction, and constitute a first expansionmechanism 94, that expand the first rod 781.

Furthermore, on the inside surface of the first axis member 79constituting the first rod 781, a plurality of air pads (air staticpressure bearing unit) 96's serving as gas static pressure bearing unitsare arranged. The gas static pressure bearing unit is a bearing unitthat supports the magnetic pole unit 90 serving as a mover of the aboveshaft motor 92 in non-contact manner with respect to the armature unit88 as a stator. Each air pad 96 has an air pressure circuit (not shown),which is connected to an air pressure source (not shown) via an airsupply path 98 and air supply tube 99, connected thereto. And via theair pressure circuit, the pressure of a compressed air supplied from theair pressure source is controlled, and the compressed air having apredetermined pressure is blown out from each air pad 96 toward theperiphery of the magnetic pole unit 90. Then by the static pressure ofthe compressed air, so-called gap-inside pressure, the magnetic poleunit 90 is supported in non-contact manner with respect to the armatureunit 88.

Therefore, a friction that is non-linear component is avoided whencontrolling the expansion/contraction of the first rod 781, where theair pad 96 is arranged, by the first expansion mechanism 941.

Furthermore, in the neighbor of this air pad 96, a differential exhaustmechanism (vacuum exhaust mechanism) 400, which is connected to a vacuumpump (not shown), is arranged. This differential exhaust mechanism 400prevents an gas blown out of the air pad 96 from contaminating the gaspurity of the atmosphere inside the exposure apparatus (e.g. helium gasatmosphere) by differentially exhausting the air blown from the air pad96.

Incidentally, the above shaft motor 92 also functions as a kind ofmagnetic bearing by controlling the phase of the driving current.However, considering the effect of the gravity exerted on the secondaxis member 80, the above air pad 96 is arranged. Therefore, instead ofthe above air pad, a magnetic bearing unit may be employed as thebearing unit.

Note that although not shown in FIG. 3, a linear encoder 95, is arrangedwhich uses a Hall device to detect the amount of movement of themagnetic unit 90 with respect to the armature unit 88 and that theoutput of the linear encoder is supplied to the main controller 50(refer to FIG. 8).

The other first rods 782, 783 are constituted in the same way as thefirst rod 78, and have first expansion mechanisms 94 ₂, 94 ₃ and linearencoders 95 ₂, 95 ₃ that are respectively the same as those of the firstrod 78 ₁ (refer to FIG. 8).

Moreover, the second mechanism comprises a second base member 102provided on the floor surface FD of a clean room and three expandablesecond rods 104 ₁, 104 ₂, 104 ₃ that each connect the second base member102 and the reticle base level block 12. As shown in FIG. 2, the secondbase member 102 comprises a basis 102 a and three extended portions 102b that extend upward from the three positions of the basis 102 a andhave the same height.

The second rods 104 ₁, 104 ₂, 104 ₃ each have a first axis member 106and a second axis member 108 that are relatively movable along theiraxis, and one end (lower end) of the first axis member 106 is attachedto a position of a predetermined height near the upper end of thecorresponding extended portions 102 b so as to be rotatable around asupporting axis 110, being a bolt or pin, as a center. And in the sameway, one end (upper end) of the second axis member 108 is attached tothe reticle base level block 12 so as to be rotatable. These threesecond rods 104 ₁, 104 ₂, 104 ₃ are so arranged that they arerespectively opposite with the first rods 78 ₁, 78 ₂, 78 ₃ in the planarview as shown in FIG. 2.

Furthermore, the second rods 104 ₁, 104 ₂, 104 ₃ respectively comprisesecond expansion mechanisms 112 ₁, 112 ₂, 112 ₃, which are composed inthe same way as the first expansion mechanisms 94, of the first rod 78₁, and linear encoders 95 ₄, 95 ₅, 95 ₆ (refer to FIG. 8). Also, in thesecond rods 104 ₁, 104 ₂, 104 ₃, air pads are arranged in the same wayand for the same purpose as the first rod.

The third mechanism comprises three third base members 114 ₁, 114 ₂, 114₃ (refer to FIG. 2) that are respectively arranged outwards next to thethree first base members 76 ₁, 76 ₂, 76 ₃ on the floor surface FD of aclean room and three expandable third rods 118 ₁, 118 ₂, 118 ₃ thatrespectively connect three third base members 114 ₁, 114 ₂, 114 ₃ withan attachment stage 116 provided on the outside of the bulkheadcontaining the projection optical system PL.

The respective third rods 118 ₁, 118 ₂, 118 ₃ have a first axis member120 and a second axis member 122 that are relatively movable along theiraxis, and one end (lower end) of the first axis member 120 is attachedto the corresponding third base member 114 so as to be rotatable arounda supporting axis 124, being a bolt or pin, as a center. And in the sameway, one end (upper end) of the second axis member 122 is attached tothe attachment stage 116 so as to be rotatable.

The third rods 118 ₁, 118 ₂, 118 ₃ respectively comprise third expansionmechanisms 126 ₁, 126 ₂, 126 ₃, which are composed in the same way asthe first expansion mechanisms 94, of the first rod 78 ₁, and linearencoders 95 ₇, 95 ₈, 95 ₉ (refer to FIG. 8). Also, in the third rods 118₁, 118 ₂, 118 ₃, air pads are arranged in the same way as the first rod.

Expansion mechanisms of rods 94 ₁ to 94 ₃, 112 ₁ to 112 ₃, 126 ₁ to 126₃ that constitute the parallel link mechanism in the way described aboveare controlled by the main controller 50 via the stage controller 52(refer to FIG. 8).

In the present embodiment, the above third mechanism composing theparallel link mechanism 74 is, for example, employed to initially setthe position and attitude of the projection optical system when startingup the exposure apparatus 10 after the completion of its assembly in afactory. That is, an operator inputs necessary information for initialsetting via an input/output unit, and the main controller 50 controlsthe third expansion mechanisms 126 ₁, 126 ₂, 126 ₃ via the stagecontroller 52 on the basis of the input information. Then the third rods118 ₁, 118 ₂, 118 ₃ are expanded and the projection optical system PL isset to be in a predetermined position and attitude. After the completionof the initial setting, the third rods 118 ₁, 118 ₂, 118 ₃ are kept inthe after-adjustment state.

Note that because there is some possibility that the Z position andattitude of the projection optical system PL changes from the initialstate due to fine deformation of the clean room floor surface over time,the above initial setting may be repeated at a predetermined timeinterval or performed as the need arises.

Next, the principle of controlling the position and attitude in threedegrees of freedom, that is θx, θy, Z, of a body (controlled object) tobe driven by a driving system having three of the same rods as the abovefirst, second and third mechanisms have will be described below.

As such a driving system, consider one, as shown schematically in FIG.4, including a stationary member T, a driven body S, and expandable rodsRD_(i) (i=one to three), each of which includes a stator side member RM1and a mover side member RM2 and links three points A_(i) (i=one tothree) of the stationary member T and three points B_(i) (i=one tothree) of the driven body S. Note that in the plane defined by threepoints A_(i) (i=one to three) these points are placed at vertices of anequilateral triangle and that as setting the center of the equilateraltriangle to be an origin O, a stationary coordinate system XYZ is sodefined that the plane including the equilateral triangle is its X-Yplane. Furthermore, in the plane defined by three points B_(i) (i=one tothree) these points are placed at vertices of an equilateral triangleand as setting the center of the equilateral triangle to be an origin P,a driven-body coordinate system UVW is so defined that the planeincluding the equilateral triangle is its U-V plane. Incidentally, ineach of the rods, the expansion/contraction of the rod RD_(i) is causedby the movement, along the line between A_(i) and B_(i), of the moverside member RM2 of the rod RD_(i).

In the present embodiment, a control system shown in FIG. 5, a blockdiagram, controls the position and attitude in three degrees of freedomθx, θy, Z, which is shown in FIG. 4, in the manner described below.

First, initial values of a position/attitude-setting portion 306 and avelocity-setting portion 304 are set to current values of the positionand attitude (θx, θy, Z), in three degrees of freedom θx, θy, Z, and thevelocities (dθx/dt, dθy/dt, dZ/dt) of a driven body S, and initialvalues of an acceleration-setting portion 302 are set to accelerationvalues (d²θx/dt², d²θy/dt², d²Z/dt²) for the control of a desirableposition/attitude. After that, until a new initial setting, only theacceleration-setting portion 302 is updated time after time. Meanwhile,in the velocity-setting portion 304, its setting values are each set tothe sum of their initial value and the integration of accelerationvalues from the acceleration-setting portion 302, and in theposition/attitude-setting portion 306, its setting values are each setto the sum of their initial value and the integration of velocity valuesfrom the velocity-setting portion 304.

At each time, a reverse-dynamics analyzing portion 308 analyzes theacceleration-setting values of the acceleration-setting portion 302, thevelocity-setting values of the velocity-setting portion 304, and theposition/attitude-setting values of the position/attitude-settingportion 306 that are set in this way and inputted thereto, and based onthe results of this analysis, the reverse-dynamics analyzing portion 308determines instructing values of thrusts for the respective rods RD_(i).

The reverse-dynamics analyzing portion 308 performs kinematical analysesregarding the position/attitude, velocity, and acceleration. These willbe described below in turn.

In the below description, for the sake of convenience, each vector isrepresented by an expression, vector XX, in sentences, and avector-symbol “→” is attached on the XX in mathematical expressions.

The Analysis of Position/Attitude

In the analysis of position/attitude, the length and theexpansion/contraction direction of each rod RD_(i) are obtained based onthe position/attitude setting values (θx, θy, Z).

Therefore, first, from the respective position vectors Bb_(i) (knownconstant vectors) of the points B_(i) (i=one to three) in the UVWcoordinate system, a vector b_(i) in the XYZ coordinate system iscalculated by the following equation (3).{overscore (b _(i))}=ARB·{overscore (Bb _(i))}  (3)

Note that ARB is a rotational transform matrix from the UVW coordinatesystem to the XYZ coordinate system and is determined by the attitudesetting values θx, θy and known θz (constant; e.g. zero) in theposition/attitude-setting portion 306. Such a rotational transformmatrix is publicly known and can be easily calculated. Incidentally,instead of the position/attitude setting values θx, θy, Z, Eulerianangles may be used and in such a case, the expression for equations ofmotion described later becomes simple.

Then using a vector b_(i) obtained from equation (3), a vector r_(i)from A_(i) to B_(i) is calculated by the following equation (4).{overscore (r_(i))}={overscore (p)}+{overscore (b _(i))}−{overscore(α_(i))}  (4)

Note that the vector p is, as shown in FIG. 4, a vector from the originO of the XYZ coordinate system to the origin P of the UVW coordinatesystem, that in the XYZ coordinate the Z component of the vector p isdetermined by a position setting value Z in theposition/attitude-setting portion 306, and that its X component and Ycomponent are known (constant; e.g. both are zero in the case of thepoint p being just on the point O). Also, a vector a_(i) is the positionvector of the point A_(i) in the XYZ coordinate system and a knownconstant vector.

Next, by the following equations (5) and (6), the length D_(i) of eachrod RD_(i) and a unit vector s_(i) in the expansion/contractiondirection of each rod RD_(i) in the XYZ coordinate system are obtained.D _(i)=|{overscore (r_(i))}|  (5){overscore (s _(i))}={overscore (r _(i))}/D _(i)  (6)

Incidentally, the reverse-dynamics analyzing portion 308 finallydetermines the thrust in the expansion/contraction direction of each rodRD_(i) and because the rotation of the rod RD_(i) is generated by theexpansion/contraction of the rod RD_(i), it is convenient to employ arod coordinate system, for each rod RD_(i), having theexpansion/contraction direction of the rod RD_(i) to be its one-axis soas to easily express the rotation of the rod RD_(i). Therefore, in thepresent embodiment, as having a X_(i)Y_(i)Z_(i) coordinate system shownin FIG. 6 represent the rod coordinate system for each rod RD_(i), thefollowing definitions are made.

That is, definitions are made that a X_(i)′Y_(i)′Z_(i)′coordinate systemis a coordinate system where its axes are respectively parallel to thoseof the XYZ coordinate system and its origin is a point A_(i), that theZ_(i)′direction and the expansion/contraction direction of the rodRD_(i) form an angle Ψ_(i), and that the X_(i)′ axis and an intersectionline between the X_(i)′Y_(i)′ plane and a plane, which is formed by theZ_(i)′ axis and the expansion/contraction direction axis of the rodRD_(i), form an angle φ_(i). Moreover, definitions are made that aX_(i)″Y_(i)″Z_(i)″ coordinate system is a coordinate system obtained byrotating the X_(i)′Y_(i)′Z_(i)′ coordinate system around the Z_(i)′ axisthrough the angle φ_(i) and that a X_(i)Y_(i)Z_(i) coordinate systemobtained by rotating the X_(i)″Y_(i)″Z_(i)″ coordinate system around theY_(i)″ axis through the angle Ψ_(i) is an individual rod coordinatesystem for the rod RD_(i).

Between the angles Ψ_(i), φ_(i) and the components (S_(ix) S_(iY)S_(iZ)) of the unit vector s_(i) in the XYZ coordinate system, thefollowing equations exist.cos φ_(i)=S_(iZ)  (7)sin φ_(i)=(s _(iX) ² +s _(iY) ²)^(1/2)  (8)sin φ_(i) =s _(iY)/sin φ₁  (9)cos φ_(i) =S _(iX)/sin φ_(i)  (10)

Moreover, a rotational transform matrix AR_(i) from the X_(i)Y_(i)Z_(i)coordinate system to the XYZ coordinate system is given by$\begin{matrix}{{AR}_{i} = \begin{pmatrix}{\cos\;{\phi_{i} \cdot \cos}\;\psi_{i}} & \; & {{- \sin}\;\phi_{i}\cos\;{\phi_{i} \cdot \sin}\;\psi_{i}} \\{\sin\;{\phi_{i} \cdot \cos}\;\psi_{i}} & \; & {{- \cos}\;\phi_{i}\sin\;{\phi_{i} \cdot \sin}\;\psi_{i}} \\{{- \sin}\;\psi_{i}} & o & {\cos\;\psi_{i}}\end{pmatrix}} & (11)\end{matrix}$

Incidentally, the rotational transform matrix AR_(i) is an Hermiteanmatrix, and the rotational transform matrix _(i)RA from the XYZcoordinate system to the X_(i)Y_(i)Z_(i) coordinate system, which is thereverse transform of the rotational transform by the rotationaltransform matrix AR_(i), is a transposed matrix.

The Analysis of Velocities

In the analysis of velocities, based on the above analysis results ofthe position and attitude and the velocity setting values, thevelocity-vectors, in the driven body connection point B_(i), of each rodRD_(i) viewed in the XYZ coordinate system and the X_(i)Y_(i)Z_(i)coordinate system and the angular-velocity-vector of each rod RD_(i)viewed in the X_(i)Y_(i)Z_(i) coordinate system are obtained.

First, the velocity-vector vb_(i) in the point B_(i) viewed in the XYZcoordinate system is obtained by{overscore (vb _(i))}={overscore (v _(P))}+{overscore(Ω_(P))}×{overscore (b _(i))}  (12)

Note that the vector V_(P) is the velocity vector of the gravity centerof the driven body S in the XYZ coordinate system, that X component andY component of the vector V_(P) are both zero because the driven body Sdoes not move in the X direction and Y direction, and that its Zcomponent is the velocity setting value dZ/dt in the velocity settingportion 304. Also, Ω_(P) represents the angular velocity vector of thedriven body S in the XYZ coordinate system, and its X component and Ycomponent respectively represent angular-velocity setting values dθx/dt,dθy/dt in the velocity-setting portion 304. Also, because the drivenbody S does not rotate about the Z-axis, its Z component is zero. Inequation (12) and below equations, “x” represents an outer productoperation and “·”an inner product operation.

Next, a velocity vector _(i)vb_(i) of the point B_(i) viewed in theX_(i)Y_(i)Z_(i) coordinate system is obtained by{overscore (_(i) vb _(i))}=_(i) RA·{overscore (vb _(i))}  (13)

Note that the Z_(i) component of vector _(i)vb_(i) represents theexpansion/contraction velocity VR_(i) of the rod RD_(i).

Next, by the following equation (14), the above unit vector s_(i) istransformed into a vector _(i)s_(i) that is its expression in theX_(i)Y_(i)Z_(i) coordinate system.{overscore (_(i) s _(i))}=_(i) RA·{overscore (s _(i))}  (14)

And a angular velocity vector _(i)Ω_(i) of the rod RD_(i) viewed in theX_(i)Y_(i)Z_(i) coordinate system is obtained by{overscore (_(i)Ω_(i))}=({overscore (_(i) s _(i))}×{overscore (_(i) vb_(i))})/D _(i)  (15)

The Analysis of Acceleration

In the analysis of acceleration, based on the above analysis results ofthe position/attitude and the velocity, and the acceleration settingvalues, the acceleration-vectors and angular-acceleration-vectors, inthe driven body connection point B_(i), of each rod RD_(i) are obtained.

Next, the acceleration-vector in the point B_(i) viewed in the XYZcoordinate system is obtained by{overscore (αb _(i))}={overscore (α_(p))}+{overscore (β_(p))}×{overscore(b _(i))}+{overscore (Ω_(p))}×({overscore (Ω_(p))}×{overscore(b_(i))})  (16)

Note that the vector α_(p) is the acceleration vector of the gravitycenter of the driven body S in the XYZ coordinate system, that Xcomponent and Y component of the vector α_(p) are both zero because thedriven body S is not driven in the X direction and Y direction, and thatits Z component is the acceleration setting value d²Z/dt² in theacceleration setting portion 302. Also, β_(P) represents the angularvelocity vector of the driven body S in the XYZ coordinate system, andits X component and Y component respectively representangular-acceleration setting values d²θx/dt², d²θy/dt² in theacceleration-setting portion 302. Also, because the driven body S is notdriven about the Z-axis, its Z component is zero.

Next, a velocity vector _(i)αb_(i) of the point B_(i) viewed in theX_(i)Y_(i)Z_(i) coordinate system is obtained by{overscore (_(i) αb _(i))}=_(i) RA·{overscore (αb _(i))}  (17)

Note that the Z_(i) component of vector _(i)αb_(i) represents theexpansion/contraction acceleration αR_(i) of the rod RD_(i).

Next, an angular-acceleration vector _(i)β_(i) of the point B_(i) viewedin the X_(i)Y_(i)Z_(i) coordinate system is obtained by{overscore (_(i)β_(i))}({overscore (_(i) s _(i))}×{overscore (_(i) αb_(i))})/D _(i)−2VR _(i)·{overscore (_(i)Ω_(i))}/D _(i)  (18)

Incidentally, each rod RD_(i) is composed of the stator side member RM1and the mover side member RM2. Assume that the structure of the statorside member RM1 and the mover side member RM2 is the one shown in FIG.7. That is, the mass of the stator side member RM1 and the mass of themover side member RM2 are respectively represented by m1 and m2. Also,assume that the gravity center of the stator side member RM1 is locatedat the position of distance L1 from the point A_(i) in the directionfrom the point A_(i) to B_(i) and that the gravity center of the moverside member RM2 is located at the position of distance L2 from the pointB_(i) in the direction from the point B_(i) to A_(i).

In this case, an acceleration vector _(i)α1_(i), in the gravity center,of the stator side member RM1 and an acceleration vector _(i)α2_(i), inthe gravity center, of the mover side member RM2 viewed in theX_(i)Y_(i)Z_(i) coordinate system are obtained by the followingequations (19), (20).{overscore (_(i)α1 ₁)}=L 1·{overscore (_(i)β_(i))}+L 1·{overscore(_(i)Ω_(i))}×({overscore (_(i)Ω_(i))}×{overscore (_(i) s _(i))})  (19){overscore (_(i)α2 _(i))}=αR _(i)·{overscore (_(i) s _(i))}+(D _(i) −L2)·{overscore (_(i)β_(i))}×{overscore (_(i) s _(i))}+(D _(i) −L2)·{overscore (_(i)Ω_(i))}×({overscore (_(i)Ω_(i))}×{overscore (_(i) s_(i))})+2 VR _(i)·{overscore (_(i)Ω_(i))}×{overscore (_(i) s_(i))}  (20)

After the completion of the analyses of the position/attitude, thevelocity/angular-velocity, and the acceleration/angular-acceleration asdescribed above, as shown in FIG. 7, by virtually dividing the drivenbody S and the rod RD_(i) at the point B_(i), the system is decomposedinto a driven body system and open loop rod system.

And considering each rod RD_(i) as a sub-system, an equation of motionabout A_(i) for the rod RD_(i) is given by{overscore (_(i) n _(i) A)}=d({overscore (_(i) h _(i) A)})/dt  (21)

Note that the vector _(i)n_(i)A_(i) is a moment vector about the pointA_(i) of the rod RD_(i) and that the vector _(i)h_(i)A_(i) is a angularmoment vector about the point A_(i) of the rod RD_(i).

Incidentally, as shown in FIG. 7, viewing in the _(i)Y_(i)Z_(i)coordinate system, a reaction _(i)fa_(i) (_(i)fa_(Xi), _(i)fa_(Yi),_(i)fa_(Zi)) acting on the rod RD_(i) is generated at the point A_(i)and a reaction {−_(i)fb_(i) (−_(i)fb_(Xi), −_(i)fb_(Yi), −_(i)fb_(Zi))acting on the rod RD_(i) is generated at the point B_(i). And a reaction_(i)fb_(i) is generated at a point of the driven body S corresponding tothe point B_(i).

The values _(i)fb_(Xi), _(i)fb_(Yi) that are respectively X_(i) axiscomponent and Y_(i) axis component of the reaction acting on the pointB_(i) and the point of the driven body S corresponding to the pointB_(i) are obtained on the basis of the results of the abovereverse-dynamics analysis of the position/attitude, the velocity/angularvelocity, the acceleration/angular acceleration, the mass m1 of thestator side member RM1, the mass m2 of the mover side member RM2, and agravity acceleration regardless of the mass of the driven body S. Also,the value _(i)fb_(Zi) that is Z_(i) axis component is obtained byresolving a translation motion equation of the driven body S viewed inthe XYZ coordinate system (22) and a rotatory equation (23).$\begin{matrix}{{{\sum\limits_{i = 1}^{3}\overset{\longrightarrow}{\left( {Afb}_{i} \right)}} + {m_{p} \cdot \overset{\longrightarrow}{g}}} = {m\;{p \cdot \overset{\longrightarrow}{\alpha_{p}}}}} & (22)\end{matrix}$ $\begin{matrix}{{Bn}_{p} = {\sum\limits_{i = 1}^{3}\left( {\overset{\longrightarrow}{{Bb}_{i}} \cdot \overset{\longrightarrow}{{Bfb}_{i}}} \right)}} & (23)\end{matrix}$

The vector Afb_(i) is a reaction-vector acting on the point of thedriven body S corresponding to the point B_(i) in the XYZ coordinatesystem and given by the following equation (24).{overscore (Afb _(i))}=AR _(i)·{overscore (_(i) fb _(i))}  (24)

Also, m_(p) represents the mass of the driven body S and a vector grepresents a gravity acceleration vector.

Furthermore, the vector Bn_(p) represents the moment of the driven bodyS viewed in the UVW coordinate system and the vector Bfb_(i) is areaction-vector acting on the point of the driven body S correspondingto the point B_(i) in the UVW coordinate system and given by thefollowing equation (25). $\begin{matrix}\begin{matrix}{\overset{\longrightarrow}{{Bfb}_{i}} = {({ARB})^{- 1} \cdot \overset{\longrightarrow}{{Afb}_{i}}}} \\{= {({ARB})^{- 1} \cdot {AR}_{i} \cdot \overset{\longrightarrow}{{}_{}^{}{}_{}^{}}}}\end{matrix} & (25)\end{matrix}$

Incidentally, although equations (22) and (23) include six equations,considering that the driven body is driven in three degrees of freedomθx, θy, Z, an equation regarding Z component of equation (24) and twoequations regarding components θx, θy of equation (25) are used oncalculating three values _(i)fb_(Zi) (i=one to three).

And the reverse-dynamics analyzing portion 308 finally calculates theinstructing value τ_(i) of thrust for each of the rods RD_(i) accordingtoτ_(i)=_(i) fb _(Zi) +m 2 ·gc· cos φ_(i) +m 2·₁α2_(Zi)  (26)

Note that _(i)fb_(Zi) is the Z component of vector _(i)fb_(i) and thatgc is the magnitude (9.8 m/S²) of the gravity acceleration.

Although, in the above, the calculation of the instructing value ofthrust for each rod RD_(i) according to Newton/Euler method isdescribed, the instructing value of thrust for each ros RD_(i) may becalculated according to d'Alembert method. In the d'Alembert method, theequations of Newton/Euler method are put together into Jacobianmatrices, and forces of constraint and moments of Newton/Euler methodare removed from the equations of motion. Therefore, it is moreefficient than Newton/Euler method, practical, and preferable d'Alembertmethod will be briefly described below. Note that symbols represent thesame things as those of Newton/Euler method.

First, in the same way as Newton/Euler method, the position/attitude,velocity/angular velocity, and acceleration/angular acceleration areanalyzed by reverse-dynamics analysis. The rotational transform matrixfrom the UVW coordinate system to the XYZ coordinate, and the angularvelocity vector Ω_(P) and angular acceleration vector β_(P) in theexpression of Eulerian angles are obtained.

Next, Jacobian matrix Jb_(i) of each rod RD_(i) regarding the XYZcoordinate system that satisfy the following equation (27) iscalculated.{overscore (vb _(i))}=Jb _(i)·{overscore (va_(p))}  (27)

Note that va_(p) is a velocity vector in six degrees of freedom in theXYZ coordinate system and the resultant of the above velocity vectorv_(P) of the gravity center of the driven body S and the angularvelocity vector Ω_(P) of the driven body S.

Jacobian matrix Jb_(i) is obtained from the results of reverse-dynamicsanalyses of the position/attitude and velocity/angular velocity by usingan equation equivalent to the equation (12).

Next, Jacobian matrix _(i)Jb_(i) of each rod RD_(i) regarding theX_(i)Y_(i)Z_(i) coordinate system is calculated by the followingequation (28)._(i) Jb _(i)=_(i) RA·Jb _(i)  (28)

By using Jacobian matrix _(i)Jb_(i), from the velocity vector va_(p) insix degrees of freedom in the XYZ coordinate system, velocity vector_(i)vb_(i) of the point B_(i) viewed in the X_(i)Y_(i)Z_(i) coordinatesystem is obtained from the following equation (29).{overscore (_(i) vb _(i))}=_(i) Jb _(i)·{overscore (va _(p))}  (29)

Next, a driven body's Jacobian matrix JP is obtained from the followingequation (30).{overscore (VR _(i))}=JP·{overscore (v _(p))}  (30)

The driven-body's Jacobian matrix JP is obtained on the basis that Z_(i)component of vector _(i)vb_(i) is the expansion/contraction velocityvector VR_(i) of the rod RD_(i).

Incidentally, considering that the gravity acts on the driven body S, aapplied-force vector fS_(p) and an inertia torque tS_(p) exerted on thegravity of the driven body S are obtained from the following equations(31) and (32) as representing an inertia matrix around the gravity ofthe driven body S in the XYZ coordinate system by AI_(p).{overscore (fS _(p))}=m _(p) ·{overscore (g)}− m _(p)·{overscore(α_(p))}  (31){overscore (tS _(p))}=−AI _(p)·{overscore (β_(p))}−{overscore(Ω_(p))}×(AI _(p)·{overscore (Ω_(p))})  (32)

The resultant of the applied-force vector fS_(p) and inertia torquetS_(p) is represented by vector T_(p) in the below.

In the same way as the driven body S, the resultant _(i)T1 _(i), in theX_(i)Y_(i)Z_(i) coordinate system, of the applied-force vector and theinertia torque that act on the gravity of the stator side member RM1composing the rod RD_(i) and the resultant _(i)T2 _(i), in theX_(i)Y_(i)Z_(i) coordinate system, of the applied-force vector and theinertia torque that act on the gravity of the mover side member RM2composing the rod RD_(i) are obtained.

Next, using the instructing value τ_(i) of thrust for each rod RD_(i) asa parameter and employing driven-body's Jacobian matrix, an equation ofmotion is established. And by solving that equation, the instructingvalue τ_(i) of thrust for each rod RD_(i) is obtained. Note that theinstructing value τ_(i) of thrust can be calculated by applying Gausselimination to the equation of motion.

That is, the instructing value τ_(i) of thrust depends on the reversetransform of the driven-body's Jacobian matrix. Therefore, because, whenthe driven body comes close to a singular point of the reversetransform, a value calculated as the instructing value τ_(i) of thrustbecomes unstable, it is necessary to monitor the amount of theexpansion/contraction, and velocity and acceleration of each rod RD_(i)all the time.

As described above, a voltage conversion portion 310 converts theinstructing value τ_(i) of thrust for each rod RD_(i) obtained by thereverse-dynamics analyzing portion 308 into a voltage supplied to eachrod RD_(i). The voltage is supplied to the electromagnetic actuator(corresponding to the shaft motor 92 in FIG. 3) of each rod RD_(i) via avoltage adder 322 and first-order delay portion 312. And by the rodRD_(i) expanding or contracting according to the voltage, the drivenbody 316 (i.e. the above driven body S (corresponding to the wafer baselevel block 38, etc.)) is driven in three degrees of freedom θx, θy, Z.

Note that taking into account time delay in the delay portion 312 andthe driven body 316, a controller 318 generates and supplies a voltageaccording to the difference between the position/attitude setting valuesin the position/attitude setting portion 306 and the position/attitudevalues measured by a stage system sensor 320 (corresponding to the focussensor 73 in FIG. 1) to the voltage adder 322. Furthermore, taking theabove time delay into account, a controller 324 generates and supplies avoltage according to the difference between the length of each rodRD_(i) calculated by the reverse-dynamics analyzing portion 308 and thelength of each rod RD_(i) measured by a rod system sensor 326(corresponding to the linear encoder 95) to the voltage adder 322. Bythis compensated voltage for each rod generated by the controller 318,324, the delay in control by the delay portion 312 or the driven body316 is compensated for.

In FIG. 8, the structure of the control system of the exposure apparatus10 is schematically shown. The control system of FIG. 8 comprises themain controller 50 and the stage controller 52, each of which iscomposed of a microcomputer or a workstation, as a main portion. Notethat the main controller 50 and the stage controller 52 comprise theacceleration-setting portion 302, the velocity-setting portion 304, theposition/attitude-setting portion 306, the reverse-dynamics analyzingportion 308, the voltage conversion portion 310, and the controllers318, 324 and control the reticle base level block 12 and the wafer baselevel block 38 using the principle of the driving control by the aboveparallel link mechanism on the basis of the detection results by thereticle interferometer 24R, the wafer interferometer 24W, the focussensor 73, and the linear encoder 95.

Next, the exposure operation by the exposure apparatus 10 of the presentembodiment, which is constituted in the manner described above, will bedescribed below with referring to FIG. 8 and the like.

Assume that, as a premise, the above initial setting of the projectionoptical system PL is completed using the third mechanism composing theparallel link mechanism 74.

First, after preparation such as reticle alignment and base linemeasurement using a reticle microscope (not shown), an off-axisalignment sensor (not shown), and the like, a fine alignment (EGA(enhanced global alignment), etc.) of a wafer W using the alignmentsensor is completed, and then the arrangement coordinates of a pluralityof shot areas on the wafer are obtained. Incidentally, the details ofthe above preparation of such as reticle alignment and base linemeasurement are disclosed in Japanese Patent Laid-Open No. 4-324923,U.S. Pat. No. 5,243,195 corresponding thereto, and the like, and thedetails of the EGA are disclosed in Japanese Patent Laid-Open No.61-44429, U.S. Pat. No. 4,780,617 corresponding thereto, and the like.The disclosures in the above Japanese Patent Laid-Opens and U.S. patentsare incorporated herein by this reference as long as the national lawsin designated states or elected states, to which this internationalapplication is applied, permit.

Next, according to the instructions from the main controller 50, thestage controller 52 moves the reticle stage RST via the reticle driver14 while monitoring the measurement values of the reticle laserinterferometer 24Ry₁, 24Ry₂, 24Rx, and the reticle is positioned at ascanning start position in the Y direction. In the same manner as this,according to the instructions from the main controller 50, the stagecontroller 52 moves the wafer stage WST via the wafer driver 40 whilemonitoring the measurement values of the wafer laser interferometer24Wy₁, 24Wy₂, 24Wx, and a corresponding shot area on the wafer ispositioned at a scanning start position in the Y direction.

Then the stage controller 52 moves the reticle stage RST and the waferstage WST respectively via the reticle driver 14 and the wafer driver 40in mutually opposite directions at a velocity ratio corresponding to theprojection magnification, and scanning exposure is performed.

By the above operation, one-scan exposure (one shot exposure) of thereticle R is completed.

Next, according to the instructions from the main controller 50, thestage controller 52 steps the wafer stage WST by one row of shot areasin the X direction and scans the wafer stage WST and the reticle stageRST each in an opposite direction to their previous direction, andperforms scanning exposure onto other shot areas on the wafer.

During the above scanning exposure, using the above driving controlprinciple, on the basis of the measurement results of focus and levelingin the exposure area on the wafer, the main controller 50 controls theexpansions/contractions of the first rods 78 ₁ to 78 ₃ via the stagecontroller 52 and respectively via the first expansion mechanisms 94 ₁to 94 ₃ composing the parallel link mechanism 74 and controls theposition/attitude in three degrees of freedom Z, θx, θy of the waferstage WST via the wafer base level block 38 so that the exposure areasare kept within the range of the focus depth of the projection opticalsystem. That is, in this manner, the main controller 50 adjusts therelative positions in three degrees of freedom Z, θx, θy of theprojection optical system PL and the wafer W (the wafer stage WST), inother words, precisely performs a focus leveling control to prevent thedeterioration of pattern transferred images due to defocus as much aspossible.

Furthermore, during the above scanning exposure, using the above drivingcontrol principle, on the basis of the position/attitude detectioninformation of the reticle base level block 12 reported from the stageunit 52 in real time, the main controller 50 feedback-controls the stagecontroller 52 and the second expansion mechanisms 112 ₁ to 112 ₃composing the parallel link mechanism 74, and controls theexpansions/contractions of the second rods 104 ₁ to 104 ₃ and theposition/attitude, in three degrees of freedom Z, θx, θy, of the reticlebase level block 12 to keep the position/attitude, in three degrees offreedom Z, θx, θy, of the reticle stage RST at a desirable state all thetime. That is, in this way, the main controller 50 adjusts the relativeposition, in three degrees of freedom θx, θy, Z, of the reticle stageRST with respect to the projection optical system PL. Therefore, evenwhen an offset load due to the movement of the reticle stage RST isexerted on the reticle base level block 12, the transfer positiondeviations, image blurs, etc., of the pattern-transferred image areeffectively suppressed.

As described above, in the exposure apparatus 10 of the presentembodiment, by the expandable first rods 78 ₁ to 78 ₃ composing thefirst mechanism of the parallel link mechanism 74 controlled by the maincontroller 50, the position/attitude, in three degrees of freedom θx,θy, Z, of the wafer base level block 38 can be controlled. Therefore,the position/attitude, in three degrees of freedom θx, θy, Z, of thewafer stage WST levitated above the wafer base level block 38 can beprecisely controlled with desirable operational-characteristics and highrigidity. That is, in the exposure apparatus 10 without a Z-tilt drivingmechanism on the wafer stage WST, by the expandable first rods 78 ₁ to78 ₃, the Z-tilt driving of the wafer W held on the wafer stage WST andthe relative position, in three degrees of freedom θx, θy, Z, of thewafer with respect to the projection optical system PL, i.e. focusleveling, can be precisely controlled with desirableoperational-characteristics and high rigidity. In this case, the threefirst rods 78 ₁to 78 ₃ support the wafer base level block 38 to beindependent of the projection optical system PL. Therefore, even whenthe wafer base level block 38 vibrates due to the reaction to thedriving force upon the drive of the wafer stage WST, the vibrationhardly transmits to the projection optical system PL. Also, in thiscase, because the Z-tilt driving mechanism is unnecessary, it ispossible to make the wafer stage WST more lightweight, and the drivingforce and driving reaction upon driving the wafer stage WST on the waferbase level block 38 by the wafer driver 40 comprising a planar motor canbe reduced.

Furthermore, in the exposure apparatus 10 of the present embodiment, theexposure main portion controls the position/attitude, in three degreesof freedom Z, θx, θy, of the reticle base level block 12 by theexpandable second rods 104 ₁to 104 ₃ composing the second mechanism ofthe parallel link mechanism 74 controlled by the main controller 50.Therefore, the position/attitude, in three degrees of freedom θx, θy, Z,of the reticle stage RST levitated above the reticle base level block 12can be precisely controlled with desirable operational-characteristicsand high rigidity. That is, in the exposure apparatus 10, without aZ-tilt driving mechanism between the reticle stage RST and the reticlebase level block 12, or on the reticle stage RST, the Z-tilt driving ofthe reticle R held on the reticle stage RST and the relative position,in three degrees of freedom θx, θy, Z, of the reticle with respect tothe projection optical system PL, i.e. focus leveling, can be preciselycontrolled by the expandable second rods 104 ₁ to 104 ₃ with desirableoperational-characteristics and high rigidity. Therefore, thedeterioration of pattern images due to reticle R's defocus caused by anoffset load, etc., exerted on the reticle base level block 12 upon themovement of the reticle stage RST can be prevented. In this case, thethree second rods 104 ₁ to 104 ₃ support the reticle base level block 12to be independent of the projection optical system PL. Therefore, evenwhen the reticle base level block 12 vibrates due to the reaction to thedriving force upon the drive of the reticle stage RST, the vibrationhardly transmits to the projection optical system PL. Also, in thiscase, because the Z-tilt driving mechanism is unnecessary, it ispossible to make the reticle stage RST more lightweight, and the drivingforce and driving reaction upon driving the reticle stage RST on thereticle base level block 12 by the reticle driver 14 comprising a linearmotor can be reduced.

Also, in this case, the wafer stage WST, the reticle stage RST, and theprojection optical system PL can be easily sealed from one another andeasily maintained.

In the present embodiment, a focus sensor 73 and a wafer laserinterferometer 24W fixed on the projection optical system PL constitutea position detector to detect the relative position, in six degrees offreedom, of the wafer W and the projection optical system. In thepresent embodiment, as described above, the driving reactions exerted onthe wafer stage WST and the reticle stage RST are prevented fromtransmitting to the projection optical system PL. Therefore, with theposition detector (the focus sensor 73 and the wafer laserinterferometer 24W) fixed on the projection optical system PL, it ispossible to precisely detect the positional relationship between theprojection optical system PL and the wafer W.

Furthermore, a position detector to detect the relative position, in sixdegrees of freedom, between the reticle stage RST and the projectionoptical system PL comprises the reticle interferometers 24Ry₁, 24Ry₂,24Rx that illuminate a movable mirror 22R provided on the reticle stageRST with a length measuring beam and detect the position, in threedegrees of freedom θx, θy, Z, of the reticle stage RST, and the first tothird interferometers 30 ₁ to 30 ₃ that illuminate a mirror 28 fixed onthe reticle base level block 12 with a length measuring beam and detectthe position, in three degrees of freedom θx, θy, Z, of the reticle baselevel block 12. In this case, the driving reactions exerted on the waferstage WST and the reticle stage RST are prevented from transmitting tothe projection optical system PL. Therefore, with the position detector(interferometers 24Ry₁, 24Ry₂, 24Rx, 30 ₁ to 30 ₃) fixed on theprojection optical system PL, it is possible to precisely detect thepositional relationship between the projection optical system PL and thereticle stage RST.

Furthermore, in the exposure apparatus 10 of the present embodiment, thefirst expansion mechanisms 94 ₁ to 94 ₃ and the second expansionmechanisms 112 ₁ to 112 ₃ that are respectively arranged in the firstrods 78 ₁ to 78 ₃ and the second rods 104 ₁ to 104 ₃ each comprise theair cylinder 84 and the shaft motor 92, a kind of electromagnetic linearmotor, that are arranged mutually in series (or in parallel). Therefore,the main controller 50 can drive the reticle base level block 12coarsely and by larger distances by controlling the air pressure of theair cylinder 84, and also finely by the shaft motor 92. As a result, themain controller 50 can precisely adjust the positions/attitudes, inthree degrees of freedom Z, θx, θy, of the wafer stage and the reticlestage, and then their relative positions with respect to the projectionoptical system PL in three degrees of freedom Z, θx, θy in a short time.That is, it is possible to perform a precise focus leveling operation ina short time.

Furthermore, because the first rods 78 ₁ to 78 ₃ and the second rods 104₁ to 104 ₃ each comprise the air pad 96 to support the magnetic poleunit 90 as the mover of the shaft motor 92 with respect to the armatureunit 88 as its stator in a non-contact manner, in controlling theexpansions and contractions of rods by the first and second expansionmechanisms, friction that works as a non-linear component can beavoided. Therefore, the positions/attitudes, in three degrees of freedomZ, θx, θy, of the wafer stage WST and the reticle stage RST can be moreprecisely controlled respectively via the wafer base level block 38 andthe reticle base level block 12.

Moreover, in the exposure apparatus 10 of the present embodiment, theshaft motors 92's are employed as electromagnetic linear motorscomposing the first expansion mechanisms 94 ₁ to 94 ₃, the secondexpansion mechanisms 112 ₁ to 112 ₃, and the third expansion mechanisms126 ₁ to 126 ₃, and in this shaft motor 92, the magnetic pole unit 90including cylindrical magnets in its mover side is employed. Therefore,magnetic flux (magnetic field) is generated radially and in alldirections, and this exposure apparatus can have the whole magnetic fluxin all directions contribute to the generation of Lorentz force (drivingforce) by an electromagnetic interaction. And then, much larger thrustcan be generated compared with a usual linear motor, etc., and it ispossible to make it smaller than a hydraulic cylinder, etc.

Therefore, the parallel link mechanism 74 where rods each comprise theshaft motor 92 is preferably applied to the exposure apparatus 10because its miniaturization and lightening, and the improvement of itsoutput are realized at the same time.

Moreover, in the exposure apparatus 10 of the present embodiment, themain controller 50 can statically adjust the relative position, withrespect to the projection optical system PL, of at least one of thewafer base level block 38 and the reticle base level block 12 by usingthe air cylinders 84's composing the first and second expansionmechanisms, and suppress vibrations by using the shaft motors 92's.Therefore, it is possible to adjust at least one of both stages WST, RSTwith respect to the projection optical system PL via at least one of thewafer base level block 38 and the reticle base level block and tosuppress the vibrations of the wafer base level block 38 and the reticlebase level block 12, which are caused by the expansions/contractions ofthe respective rods and the reactions due to the drives of the stages.

Furthermore, with the main controller 50, it is possible to suppresslow-frequency vibrations by controlling the air pressures of the aircylinders 84's composing the first and second expansion mechanisms andto insulate high-frequency vibrations by controlling the currents of theshaft motors 92's. Therefore, it is possible to suppress thelow-frequency vibrations of the wafer base level block 38 and thereticle base level block 12 due to the reactions to the drives of thestages and to insulate fine vibrations, high-frequency vibrations, fromthe floor surface.

Furthermore, the exposure apparatus 10 of the present embodimentcomprises a reticle room 18 containing the reticle stage RST andpartially including the reticle base level block 12, the lens room 32containing the projection optical system PL, the wafer room 44containing the wafer stage WST and partially including the wafer baselevel block 38, and the chamber 46 including expandable bellows-likemembers 34, 36 respectively linking the reticle room 18 and the lensroom 32, and the lens room 32 and the wafer room 44 to isolate the waferstage WST, the projection optical system PL, and the reticle stage RSTfrom the outside atmosphere. Therefore, by the parallel link mechanism74, the positions/attitudes, in three degrees of freedom Z, θx, θy, ofthe wafer base level block 38 and the reticle base level block 12 can beadjusted without any troubles. Moreover, because the wafer stage WST,the projection optical system PL, and the reticle stage RST are isolatedfrom the outside atmosphere by the chamber 46, by filling the inside ofthe chamber 46 with a gas such as nitrogen (N₂) or helium (He), it ispossible to transfer a fine pattern on the reticle onto the wafer usingthe ArF excimer laser or a vacuum ultraviolet having a shorterwavelength such as F₂ laser light.

With the exposure apparatus 10 of the present embodiment, with a numberof schemes described above, it is possible to improve the lightening andthe position controllability of the wafer stage WST and the reticlestage RST, and the exposure apparatus is excellent in thecharacteristics of suppressing vibrations of its units and isolatingvibrations of the floor, has a large number of the degrees of freedom inadjusting the stages that can be separated from each other, and canperform exposure with high resolution with using F₂ laser light or anenergy beam of a shorter wavelength in the atmosphere filled with a gassuch as helium. And it is possible to manufacture highly integratedsemiconductor devices, which have finer line widths, with high yield.

Incidentally, the above embodiment described the case where theprojection optical system PL is supported by the three third rods 118 ₁,118 ₂, 118 ₃ composing the third mechanism of the parallel linkmechanism. This is because the initial adjustment of the projectionoptical system PL can be easily done by individually controlling thethird expansion mechanisms 126 ₁, 126 ₂, 126 ₃ to respectivelyexpand/contract the third rods 118 ₁, 118 ₂, 118 ₃. However, because theprojection optical system PL does not intrinsically need the change ofits position/attitude afterward once its position/attitude is set at adesirable state, a supporting mechanism to support the projectionoptical system PL to be fixed on the floor surface FD may be providedinstead of the third mechanism. Even in this case, because thepositions/attitudes, in three degrees of freedom Z, θx, θy, of the waferstage WST and the reticle stage RST, the positional relationships, inthree degrees of freedom Z, θx, θy, of the wafer W and retcile R withrespect to the projection optical system PL are adjustable.

Also, in the above embodiment, the third expansion mechanisms 126 ₁ to126 ₃ each have the air cylinder and shaft motor, however, the thirdexpansion mechanisms may each have only the air cylinder. Even in thiscase, the initial position/attitude of the projection optical system PLcan be easily adjusted by adjusting the inside pressure of the aircylinder.

Furthermore, in the above embodiment, bilaterally telecentricoptical-system is employed as the projection optical system PL. However,the present invention is not limited to this, not to mention. Forexample, as the projection optical system, an optical system that isnon-telecentric in its object side may be employed. In such an opticalsystem non-telecentric in its object side, although the defocus of thereticle R is one factor of the deviation of transfer position of thepattern image, the deviation of transfer position of the pattern imagedue to the defocus of the reticle R can be prevented because, in theabove embodiment, the position, in three degrees of freedom Z, θx, θy,of the reticle R is controlled in the above manner.

Incidentally, in the above embodiment, the case where the first basemembers 76 ₁, 76 ₂, 76 ₃, the second base member 102, and the third basemembers 114 ₁, 114 ₂, 114 ₃ each are individual members was described.However, at least either the first base members or the third members maybe one common member, or at least any two out of the first, second andthird base members may be one common member. That is, all of the first,second and third base members may be one common member, or the first andsecond, the second and third, or the first and third base members may beone common member.

Moreover, in the above embodiment, the case was described where a stageis mounted both the wafer base level block 38 and the reticle base levelblock 12. However, a plurality of stages may be mounted at least eitheron the wafer base level block 38 or on the reticle base level block 12.For example, in a case where a plurality of wafer stages WST are mountedon the wafer base level block 38, during the exposure operation of onewafer on the wafer stage, change of wafers on another wafer stage, orother operations such as the detection of wafer alignment marks can besimultaneously performed. Therefore, the throughput can be improvedcompared with a case of having only one wafer stage. Also, for example,in a case where a plurality of reticle stages RST are mounted on thereticle base level block 12, because reticles can be changed byexchanging the positions of those plurality of reticle stages, it ispossible to improve the throughput of such multi-exposure using aplurality of reticles as double exposure. Especially, in a case where aplurality of wafer stages WST and reticle stages RST are provided,during multi-exposure of a wafer on one wafer stage, such otheroperations as wafer change on another wafer stage and the detection ofwafer alignment marks can be simultaneously performed. Therefore, suchmulti exposure using a plurality of reticles as double exposure can beperformed with a high throughput.

Moreover, in the above embodiment, the case is described where the waferbase level block 38 and the reticle base level block 12 are respectivelysupported by the first mechanism and the second mechanism of theparallel link mechanism 74 so as to be controllable in their attitudes.However, the present invention is not limited to this, not to mention.That is, only one of the wafer base level block 38 and the reticle baselevel block 12 may be supported by the parallel link mechanism. Even insuch a case, the position/attitude of a level block, which is supportedby the parallel link mechanism and serves as an end-effector of theparallel link mechanism, can be controlled in the same manner as above,and as a result, the above effects are obtained.

Furthermore, the structure of the chamber 46 described in the aboveembodiment shows only one example, and the present invention is notlimited to this, not to mention. That is, in the exposure apparatus ofthe present invention, any chamber can be used which contains at leastone portion of the exposure apparatus's main portion (the reticle stageRST, the projection optical system PL, the wafer stage WST, etc.), whichare supported by the parallel link mechanism, to be isolated from theoutside atmosphere and allows the change of its attitude. In such acase, a portion of the exposure apparatus's main portion supported bythe parallel link mechanism can be made lightweight by using theadvantages of the parallel link mechanism, and its attitude can beprecisely controlled with desirable operational-characteristics and highrigidity. Also, because the chamber houses at least one portion of theexposure apparatus's main portion to be isolated from the outsideatmosphere and allowed to change its attitude, it is possible totransfer a fine pattern on the reticle onto the wafer using the ArFexcimer laser or a vacuum ultraviolet having a shorter wavelength suchas F₂ laser light by filling the inside of the chamber with a gas suchas nitrogen (N₂) or helium (He).

Furthermore, in the above embodiment, at least a portion of theillumination optical system IOP may be supported by the parallel linkmechanism.

A Second Embodiment

A second embodiment of the present invention will be described belowwith referring to FIGS. 9 to 17. Hereafter, the same or equivalentelements to those of the above first embodiment are represented by thesame numbers, and for each of them, a brief or no description will bepresented.

Moreover, the first and second embodiments can be employed incombination as the need arises.

FIG. 9 schematically shows an exposure apparatus 130 according to thesecond embodiment. This exposure apparatus is a scanning-type exposureapparatus based on a step-and-scan method, i.e. a scanning stepper,which transfers a pattern on a reticle onto a plurality of shot areas ona wafer while illuminating the reticle as a mask with an exposureillumination light EL and synchronously moving the reticle and the waferas a substrate in a predetermined direction (hereafter, set to be Y axisdirection perpendicular to the drawing of FIG. 9).

In this exposure apparatus 130, a reticle stage RST as a mask stage anda stage that is triangle in a planar view and serves as a substrate orwafer stage are employed, and its feature is that these stages arecontrolled in the six degrees of freedom X, Y, Z, θx, θy, θz by theparallel link mechanism.

This exposure apparatus 130 comprises an illumination optical systemIOP, the reticle stage RST holding the reticle R, the wafer stage WSTholding the wafer W, a first parallel link mechanism 132 including thewafer stage WST as an end-effector, a second parallel link mechanism 134including the reticle stage RST as an end-effector, and the like.

The first parallel link mechanism 132 comprises, as shown in FIG. 10, afirst base member 136 that is almost horizontally arranged on the floorsurface FD of a clean room and shaped in a regular hexagon; sixexpandable first rods 178 ₁ to 178 ₆ that each link the first basemember 136 and the wafer stage; and first expansion mechanisms 194 ₁ to194 ₆ (not shown in FIG. 9; refer to FIG. 17) that are mountedrespectively in the first rods 178, to 178 ₆ and each expand/contracttheir first rod.

As the first rods 178 ₁ to 178 ₆, rods each comprising a first axismember and a second axis member that can relatively move in their axisdirection in the same manner as the first rod 78 ₁ in the above firstembodiment are used. And the first axis member and second axis membercomposing each of the first rods 178 ₁ to 178 ₆ are relatively driven byrespective one of first expansion mechanisms 194 ₁ to 194 ₆ that are thesame as the first expansion mechanism 94 ₁ consisting of the aircylinder and shaft motor. Also, linear encoders 95 ₁ to 95 ₆ (refer toFIG. 17), each of which employs a Hall device to detect the amount ofmovement of a magnetic pole unit with respect to an armature unit in ashaft motor composing respective one of the first expansion mechanisms194 ₁ to 194 ₆, and air pads to levitate and support the magnetic oleunit with respect to the armature unit in a non-contact manner aremounted in the first rods 178 ₁ to 178 ₆.

In this case, as is obvious in FIG. 10, the both sides of each of thefirst rods 178 ₁ to 178 ₆ are connected respectively to the first basemember 136 and the wafer stage WST via universal joints 138's. Also, thefirst rods 178 ₁, 178 ₂ are connected around a vertex of the trianglewafer stage WST, and the first base member 136 and the first rods 178 ₁,178 ₂ form an almost triangle. In the same manner as this, the rods1783, 1784 and the rods 178 ₅, 178 ₆ are respectively connected aroundthe other vertices of the triangle wafer stage WST, and the first basemember 136 and the rods 178 ₃, 178 ₄, and the first base member 136 andthe rods 178 ₅, 178 ₆ each form an almost triangle.

The main controller 50 receives the outputs of the linear encoders 95 ₁to 95 ₆ and controls the first expansion mechanisms 194 ₁ to 194 ₆ onthe basis of the outputs of the linear encoders 95 ₁ to 95 ₆ via thestage controller 52 (refer to FIG. 17).

Referring back to FIG. 9, the projection optical system PL is held on alens-barrel level block 144 almost horizontally supported via fourcolumns 140 fixed on the floor surface FD and vibration preventing units142 mounted on the columns 140.

The lens-barrel level block 144 is constituted of, e.g., castings, andan circular opening in a planar view is formed in its center and theprojection optical system PL is inserted into the opening from abovesuch that its optical axis coincides with the Z axis direction. On theperiphery of the projection optical system PL, a flange FLG, which isintegrated with the lens-barrel, is provided. As a material of thisflange FLG, a material of low thermal expansion such as inver (aniron-alloy with nickel 36%, manganese 0.25%, and a small amount ofcarbon and other elements) is used, and this flange FLG composes akinematic supporting mount supporting the projection optical system PLagainst the lens-barrel level block 144 at three points via points,surfaces, and V-shape grooves. By using such a kinetic supportingstructure, it is easy to attach the projection optical system PL to thelens-barrel level block 144, and there is also an advantage that afterthe attachment, stress due to vibrations, the temperature changes,attitude changes, and the like of the lens-barrel level block 144 andthe projection optical system PL can be reduced most effectively.

In this case, the vibration-preventing unit 142 insulates finevibrations transmitted from the floor surface to the lens-barrel levelblock 144 at micro G level. In the present embodiment, the supportingcolumn 140, the vibration-preventing unit 142, and the lens-barrel levelblock 144 compose a supporting mechanism to fix and support theprojection optical system PL on the floor surface FD where the mainportion of the exposure apparatus is arranged.

On the wafer stage WST, the wafer W is held by chucking, and theposition of the wafer stage in X-Y plane is detected with resolution of0.5 to 1 nm by the wafer laser interferometer system consisting of thethree interferometers 24Wx₁, 24Wx₂, 24Wy shown in FIG. 11.

To be more specific, the interferometer 24Wx₁ is fixed on thelens-barrel level block 144 and hangs from it. And a first reflectionsurface 146 a formed on the side surface of the wafer stage WST isvertically illuminated with measurement beams WIX1, WIX3 in a directionforming a predetermined angle θ₁ (hereafter, +60°) with respect to the Yaxis. The measurement beam WIX1 is shined toward the optical axis of theprojection optical system PL. A fixed mirror Mw1, on which a referencebeam corresponding to this measurement beam WIX1 is incident, is fixedon the side surface of the projection optical system PL (refer to FIG.9), and the measurement beam WIX3 is shined toward the detection centerof an off-axis-alignment detection system ALG. A fixed mirror (notshown) on which a reference beam corresponding to this measurement beamWIX3 is incident is fixed on the side surface of an off-axis-alignmentdetection system ALG.

Furthermore, the interferometer 24Wx₂ is fixed on the lens-barrel levelblock 144 and hangs from it. And a third reflection surface 146 c formedon the side surface of the wafer stage WST is vertically illuminatedwith measurement beams WIX2, WIX4 in a direction forming a predeterminedangle θ₂ (hereafter, −60°) with respect to the Y axis. The extensionline of the optical path of the measurement beam WIX2 crosses theextension line of the exposure light of the measurement beam WIX1. Afixed mirror Mw2, on which a reference beam corresponding to thismeasurement beam WIX2 is incident, is fixed on the side surface of theprojection optical system PL (refer to FIG. 9), and the extension lineof the optical path of the measurement beam WIX4 crosses the extensionline of the optical path of the measurement beam WIX3 at the center ofthe off-axis-alignment detection system ALG. A fixed mirror (not shown)on which a reference beam corresponding to this measurement beam WIX4 isincident is fixed on the side surface of an off-axis-alignment detectionsystem ALG.

Moreover, the interferometer 24Wy is fixed on the lens-barrel levelblock 144 and hangs from it. And a second reflection surface 146 bformed on the side surface of the wafer stage WST is verticallyilluminated with measurement beams WIY1, WIY2 in the Y axis direction.These measurement beams WIY1, WIY2 pass along optical paths bilaterallysymmetric with respect to the Y axis between the optical axis of theprojection optical system PL and the detection center of the alignmentdetection system ALG. A fixed mirror (not shown) on which referencebeams corresponding to these measurement beams WIY1, WIY2 are incidentis fixed on the side surface of the projection optical system.

The measurement values of the above interferometers 24Wx₁, 24Wx₂, 24Wyare supplied to the stage controller 52 nd then the main controller 50(refer to FIG. 17). The stage controller 52 calculates the Y position ofthe wafer stage WST on the basis of the average value of measurementvalues by the measurement beams WIY1, WIY2 of the interferometer 24Wy,and calculates the θz rotation (yawing) of the wafer stage WST on thebasis of the difference of the above two measurement values and thedistance between the measurement axes.

Furthermore, the stage controller 52 calculates the X position of thewafer stage WST on the basis of a measurement value X1 of theinterferometer 24Wx₁ and a measurement value X2 of the interferometer24Wx₂using the following equation (33).X={(X 1/|sin θ₁|)−(X 2/|sin θ₂|)}/2  (33)

Because |sin θ₁|=|sin θ₂|=sin θ, the X coordinate position of the waferstage WST is given byX=(X 1−X 2)/(2 sin θ)  (33′).

Note that because it is important to avoid a so-called Abbe error, uponexposure operation, the stage controller 52 calculates the X position ofthe wafer stage WST using the above equation (33′) on the basis of themeasurement values by the measurement beams WIX1, WIX2 shined from theinterferometers 24Wx₁, 24Wx₂ toward the optical axis of the projectionoptical system PL, and upon alignment, calculates the X position of thewafer stage WST using the above equation (33′) on the basis of themeasurement values by the measurement beams WIX3, WIX4 shined from theinterferometers 24Wx₁, 24Wx₂ toward the detection center of thealignment detection system ALG.

The positional information, in the degrees of freedom X, Y, θz, of thewafer stage WST obtained above is reported from the stage controller 52to the main controller 50 in real time.

Incidentally, in the present embodiment, it is preferable to compose theinterferometer having a measurement axis corresponding to each ofmeasurement beams to have a so-called double-path structure so as toprevent fine yawing (θz rotation) of the wafer stage from affecting theaccuracy of exposure, and it is also preferable to compensate for aso-called Abbe error due to the difference in height between theinterferometer measurement axis and the surface of the wafer W.Specifically, it is preferable to make other measurement beams incident,for example, below or above the measurement beams WIX1, WIX2 and WIY1(or WIY2), measure the pitching and rolling of the wafer stage WST, andcorrect X-Y position information of the wafer stage WST calculated aboveon the basis of these results.

On the upper surface of the wafer stage WST, as shown in FIG. 11, areference mark plate FM where reference marks for base line measurementand other reference marks of the alignment detection system are formedis arranged.

Referring back to FIG. 9, the second parallel link mechanism 134 ismounted on a gate-shape frame 152 constituted of a pair of verticalmembers 148A, 148B and a horizontal plate 150 supported by thesevertical members 148A, 148B. The horizontal plate 150 has an opening ina predetermined shape formed in its almost center.

The second parallel link mechanism 134 is structured in the same way asthe first parallel link mechanism 132. That is, the second parallel linkmechanism 134 comprises a second base member 154 that is arranged on thegate-shape frame 152, has an opening, which is almost equal to theopening of the horizontal plate 150 in shape and size, formed in itscenter, and is shaped in a regular hexagon; six expandable second rods179 ₁ to 179 ₆ that each link the second base member 154 and the reticlestage RST via their universal joints; and second expansion mechanisms195 ₁ to 195 ₆ (not shown in FIG. 9; refer to FIG. 17) that are mountedrespectively in the second rods 179 ₁ to 179 ₆ and each expand/contracttheir second rod. As the second rods 179 ₁ to 179 ₆, rods having thesame structure as the first rod 78 ₁ are employed, and as the secondexpansion mechanisms 195 ₁ to 195 ₆, mechanisms having the samestructure as the first expansion mechanism 94 ₁ are employed. Linearencoders 95 ₇ to 95 ₁₂ each of which employs a Hall device to detect theamount of movement of a magnetic pole unit with respect to an armatureunit in shaft motor composing respective one of the first expansionmechanisms 195 ₁ to 195 ₆, and air pads to levitate and support themagnetic pole unit with respect to the armature unit in a non-contactmanner are mounted in the second rods 179 ₁ to 179 ₆.

The output of the linear encoders 95 ₇ to 95 ₁ are supplied to the maincontroller 50, and based on the output of the linear encoders 95 ₇ to 95₁₂, the main controller 50 controls the second expansion mechanisms 195₁ to 195 ₆ via the stage controller 52 (refer to FIG. 17).

The position of the reticle stage RST in the X-Y plane is detected bythree interferometers 24Rx₁, 24Rx₂, 24Ry (the interferometer 24Rylocated at the back of the drawing is not shown in FIG. 9; refer to FIG.17) fixed on the horizontal plate 150 of the gate-shape frame 152, e.g.,with resolution of 0.5 to 1 nm. This position is detected with fixedmirrors Mr₁, Mr₂, Mr₃ (the mirror Mr₃ located at the back of the drawingis not shown) as references fixed on the side surface of the lens-barrelof the projection optical system PL. In the same way as the above, thestage controller 52 calculates the position, in the degrees of freedomX, Y, θz, of the reticle stage RST, and the positional information, inthe degrees of freedom X, Y, θz, of the reticle stage RST is reportedfrom the stage controller 52 to the main controller 50 in real time.

As the alignment detection system ALG, for example, an imaging-typealignment sensor is employed which illuminates alignment marks (or thereference mark plate FM) on the wafer with a broad band light, receivesits reflection light, and detects the marks by image processing. Thedetails of such an imaging-type alignment sensor are disclosed inJapanese Patent Laid-Open No. 7-321030, U.S. Pat. No. 5,721,605corresponding thereto, and the like. The disclosures in the aboveJapanese Patent Laid-Open and U.S. patent are incorporated herein bythis reference as long as the national laws in designated states orelected states, to which this international application is applied,permit.

The measurement values of the alignment detection system ALG aresupplied to the main controller 50 (refer to FIG. 17).

Incidentally, as the alignment detection system ALG, an alignment sensorof LIA (Laser Interferometric Alignment) method may be used whichilluminates grating marks on a wafer with a laser light in twodirections, has their diffracted lights interfere with each other, anddetects the positions of the grating marks on the basis of the phase ofthe interfered light.

Furthermore, a focus sensor 73 (73 a, 73 b) is arranged on the sidesurface of the projection optical system PL; the outputs of the focussensor 73 are supplied to the stage controller 52, and the stagecontroller 52 calculates the relative position, with respect to theprojection optical system PL, of the wafer in the degrees of freedom Z,θx, θy, specifically, Z position (an amount of defocus), θx rotation (anamount of pitching), θy rotation (an amount of rolling), of the exposurearea on the wafer surface on the basis of the outputs of the focussensor 73. These results, i.e. focus leveling measurement results, ofthe exposure area of the wafer are reported to the main controller 50 inreal time.

Moreover, a focus sensor 173 (not shown in FIG. 9; Refer to FIG. 17)that is a multi focal position detection system, being the same as thefocus sensor 73, and detects Z position of the pattern surface of thereticle with respect to the projection optical system PL is arrangedaround the reticle stage RST, and the output of the focus sensor 173 issupplied to the stage controller 52. Then the stage controller 52calculates the relative position, with respect to the projection opticalsystem PL, of the reticle in the degrees of freedom Z, θx, θy, in otherwords, Z position (an amount of defocus), θx rotation (an amount ofpitching), θy rotation (an amount of rolling), of the pattern surface ofthe reticle on the basis of the outputs of the focus sensor 173. Theseresults, i.e. focus leveling measurement results, of the reticle arereported to the main controller 50 in real time.

Next, the principle of controlling the position/attitude of a drivenbody in the six degrees of freedom X, Y, Z, θx, θy, θz by a drivingsystem that has six rods like the parallel link mechanism of the presentembodiment will be described below.

As such a driving system, consider a driving system, as schematicallyshown in FIG. 12, comprising a stationary member T, a driven body S, astator side member RM1, a mover side member RM2 and expandable rodsRD_(i) (i=one to six) linking six points A_(i) (i=one to six) of thestationary member T and six points B_(i) (i=one to six) of the drivenbody S. Hereafter, six points A_(i) (i=one to six) are located in oneplane and a stationary coordinate XYZ is so defined that that plane isits X-Y plane and the center of those points is its origin O, and sixpoints B_(i) (i=one to six) are located in one plane and a stationarycoordinate UYW is so defined that that plane is its U-V plane and thecenter of those points is its origin P. Note that theexpansion/contraction of each rod RD_(i) is generated by its mover sidemember RM2 moving along the straight line between the point A_(i) andthe point B_(i).

In the present embodiment, in the driving system of FIG. 12, a controlsystem, the block diagram of which is obtained by extending that in FIG.5 for the three degrees of freedom into the six degrees of freedom,controls the position/attitude in the six degrees of freedom X, Y, Z,θx, θy, θz.

That is, initial values of the velocity-setting portion 304 and theposition/attitude-setting portion 306 are set to current values for theposition/attitude (X, Y, Z, θx, θy, θz) of the driven body S in the sixdegrees of freedom X, Y, Z, θx, θy, θz and velocities (dX/dt, dY/dt,dZ/dt, dθx/dt, dθy/dt, dθz/dt), and initial values of theacceleration-setting portion 302 are set to desirable accelerationvalues for controlling the position/attitude (d²X/dt², d²Y/dt², d²Z/dt²,d²⁰θx/dt², d²⁰θy/dt², d² θz/dt²). After that, until a new initialsetting, only the acceleration-setting portion 302 is updated time aftertime. Meanwhile, in the velocity-setting portion 304, its setting valuesare each set to the sum of their initial value and the integration ofacceleration values from the acceleration-setting portion 302, and inthe position/attitude-setting portion 306, its setting values are eachset to the sum of their initial value and the integration of velocityvalues from the velocity-setting portion 304.

At each time, in the same way as in the three degrees of freedomdescribed previously, a reverse-dynamics analyzing portion 308 analyzesthe acceleration-setting values of the acceleration-setting portion 302,the velocity-setting values of the velocity-setting portion 304, and theposition/attitude-setting values of the position/attitude-settingportion 306 that are set in this way and input thereto, and based on theresults of this analysis, the reverse-dynamics analyzing portion 308determines instructing values of thrusts for the each rod RD_(i). In thesame way as in the three degrees of freedom described previously, theposition/attitude of the driven body S in the six degrees of freedom iscontrolled.

Next, a way where the first parallel link mechanism 132 controls theposition/attitude of the wafer stage WST in the six degrees of freedomwill be described below with referring to FIG. 13 to FIG. 16.

The main controller 50 can move the wafer stage WST by a distance L1 ina non-scanning direction, i.e. the X-direction, by controlling theexpansion/contraction of the first rods 178 ₁ to 178 ₆ via the firstexpansion mechanisms 194 ₁ to 194 ₆ and, e.g., changing a state of thefirst rods 178 ₁ to 178 ₆ shown by solid lines in FIG. 13 to anotherstate shown by virtual lines (two-dot chain lines). In the same way asthis, the main controller 50 can move the wafer stage WST in a scanningdirection, i.e. the Y-direction, by appropriately controlling theexpansions/contractions of the first rods 178 ₁ to 178 ₆ via the firstexpansion mechanisms 194 ₁ to 194 ₆.

Furthermore, the main controller 50 can move the wafer stage WST by adistance L2 upwards in Z-axis direction by controlling theexpansions/contractions of the first rods 178 ₁ to 178 ₆ via the firstexpansion mechanisms 194 ₁ to 194 ₆ and, e.g., changing a state of thefirst rods 178 ₁ to 178 ₆ shown by solid lines in FIG. 14 to anotherstate shown by virtual lines (two-dot chain lines). Note that there isno possibility of the interferometer's measurement-beam getting out ofthe reflection surface due to the up/down movement of the wafer stagebecause a stroke of movement in Z-axis direction is, e.g., about 100 umin practice.

Moreover, the main controller 50 can rotate the wafer stage WST througha fine angle φ₁ about the Y-axis passing through the gravity center ofthe wafer stage by controlling the expansions/contractions of the firstrods 178 ₁ to 178 ₆ via the first expansion mechanisms 194 ₁ to 194 ₆and changing a state of the first rods 178 ₁ to 178 ₆ shown by solidlines in FIG. 15 to another state shown by virtual lines (two-dot chainlines). Therefore, θy rotation (an amount of rolling) of the wafer stageWST is adjustable. In the same way as this, the main controller 50 canadjust θx rotation (an amount of pitching) of the wafer stage WST byappropriately controlling the expansions/contractions of the first rods178 ₁ to 178 ₆ via the first expansion mechanisms 194 ₁ to 194 ₆.

Also, the main controller 50 can rotate the wafer stage WST through afine angle φ₂ about the Z-axis passing through the gravity center of thewafer stage by controlling the expansions/contractions of the first rods178 ₁ to 178 ₆ via the first expansion mechanisms 194 ₁ to 194 ₆ and,e.g., changing a state of the first rods 178 ₁ to 178 ₆ shown by solidlines in FIG. 16 to another state shown by virtual lines. Therefore, θzrotation (an amount of yawing) of the wafer stage WST is adjustable.

As described above, in the present embodiment, the position/attitude ofthe wafer stage WST in the six degrees of freedom can be controlled bythe first parallel link mechanism 132.

In the same way as the above, the main controller 50 can control theposition/attitude of the reticle stage RST in the six degrees of freedomby appropriately controlling the expansions/contractions of the sixsecond rods 179 ₁ to 179 ₆ of the second parallel link mechanism 134 viathe first expansion mechanisms 195 ₁ to 195 ₆.

FIG. 17 schematically shows the structure of the control system of theexposure apparatus 130. this control system in FIG. 17 is composed ofthe main controller 50 and the stage controller 52 as its main portioneach of which is a microcomputer or workstation.

Next, the operation of exposure by the exposure apparatus 130 of thepresent embodiment will be described below with referring to FIG. 17,etc.

First, in the same manner as the first embodiment, after preparationsuch as reticle alignment and base line measurement using a reticlemicroscope, an alignment detection system ALG, a reference mark plateFM, and the like (all are not shown), a fine alignment (EGA (enhancedglobal alignment) etc.) of a wafer W using the alignment detectionsystem ALG is completed, and then the arrangement coordinates of aplurality of shot areas on the wafer are obtained. During suchpreparations, the main controller 50 moves the wafer stage WST via thestage controller 52 by using the above driving principle and controllingthe first expansion mechanisms 194 ₁ to 194 ₆ composing the firstparallel link mechanism 132.

Next, using the above driving principle, on the basis of the positionalinformation, in the degrees of freedom X, Y, θz, of the reticle stageRST reported from the stage unit 52 in real time, the main controller 50controls the expansions/contractions of the second rods 179 ₁ to 179 ₆via the stage controller 52 by using the second expansion mechanisms 195₁ to 195 ₆ composing the second parallel link mechanism 134, moves thereticle stage RST, and positions the reticle R at the scanning startpoint in the Y direction. In the same way, using the above drivingprinciple, on the basis of the positional information, in the degrees offreedom X, Y, θz, of the wafer stage WST reported from the stage unit 52in real time, the main controller 50 controls theexpansions/contractions of the first rods 178 ₁ to 178 ₆ via the stagecontroller 52 by using the first expansion mechanisms 194 ₁ to 194 ₆composing the first parallel link mechanism 132, moves the wafer stageWST, and positions a corresponding shot area on the wafer W at thescanning start point in the Y direction.

Then using the above driving principle, on the basis of the positionalinformation, in the degrees of freedom X, Y, θz, of the reticle stageRST and the wafer stage WST reported from the stage unit 52 in realtime, the main controller 50 synchronously moves the reticle stage RSTand the wafer stage WST in mutually opposite directions at a velocityratio corresponding to the projection magnification by controlling thefirst and second parallel link mechanisms 132, 134, and scanningexposure is performed.

On this scanning exposure, the main controller 50 controls thevelocities of the six first rods 178 and the six second rods 179,respectively composing the first parallel link mechanism 132 and thesecond parallel link mechanism 134, as a consequence of the positionalcontrol of each stage based on the above driving principle.

By the above operation, one-scan exposure (one shot exposure) of thereticle R is completed.

Next, according to instructions from the main controller 50, the stagecontroller 52 steps the wafer stage WST by one row of shot areas in theX direction, and scans the wafer stage WST and the reticle stage RSTeach in an opposite direction to their previous direction, and performsscanning exposure onto other shot areas on the wafer.

During the above scanning exposure, on the basis of the measurementresults of focus and leveling in the exposure area on the wafer reportedfrom the stage controller 52 in real time, the main controller 50calculates such Z, θx, θy of the wafer stage WST as the exposure areasare kept within the range of the focus depth of the projection opticalsystem PL by, calculates acceleration values to realize theposition/attitude given by those values, and gives them to the stageunit 52. By this, on the basis of the acceleration values, the stagecontroller 52 controls the first expansion mechanisms 194 ₁ to 194 ₆composing the first parallel link mechanism 132, controls theexpansions/contractions of the first rods 178 ₁ to 178 ₆, and controlsthe position/attitude in three degrees of freedom Z, θx, θy of the waferstage WST and its position/attitude in the degrees of freedom X, Y, θzsimultaneously. That is, in this way, the adjustment of the relativeposition, in three degrees of freedom Z, θx, θy, between the projectionoptical system and the wafer W (wafer stage WST), i.e. a focus levelingcontrol, is precisely performed to prevent the deterioration ofpattern-transferred images due to defocus as much as possible.

Furthermore, during the above scanning exposure, on the basis of themeasurement results of focus and leveling in the exposure area on thewafer reported from the stage controller 52 in real time, the maincontroller 50 calculates Z, θx, θy of the reticle stage RST, calculatesacceleration values to realize the position/attitude given by thosevalues, and gives them to the stage unit 52 to keep theposition/attitude, in the degrees of freedom Z, θx, θy, of the reticlestage RST at a desirable state. On the basis of the acceleration values,the stage controller 52 controls the second expansion mechanisms 195 ₁to 195 ₆ composing the parallel link mechanism 134, controls theexpansions/contractions of the second rods 179 ₁ to 179 ₆, and controlsthe position/attitude in three degrees of freedom Z, θx, θy of thereticle stage RST and its position/attitude in the degrees of freedom X,Y, θz simultaneously. That is, in this way, the relative position, inthree degrees of freedom Z, θx, θy, of the reticle stage RST withrespect to the projection optical system PL is adjusted. Therefore, thetransfer position deviations, image blurs, etc., of pattern-transferredimages due to defocus, etc., are effectively suppressed.

As described above, in the exposure apparatus 130 of the secondembodiment, the main controller 50 expands and contracts individuallythe first rods 178 ₁ to 178 ₆ by using the first expansion mechanisms194 ₁ to 194 ₆ composing the first parallel link mechanism 132 via thestage controller 52, thereby precisely controlling theposition/attitude, in the six degrees of freedom (X, Y, Z, θx, θy, θz),of the wafer stage WST with desirable operational-characteristic andhigh rigidity. Because the wafer stage WST is driven by the firstparallel link mechanism 132, such a driver to drive the wafer stage WSTas a linear motor and a stage base (wafer base level block) to supportthe wafer stage WST are unnecessary. Also, it is unnecessary to providea Z-tilt driving mechanism, etc., on the wafer stage WST. Therefore, itis possible to make the wafer stage WST small and lightweight.

In the exposure apparatus 130 of the present embodiment, the maincontroller 50 expands and contracts individually the second rods 179 ₁to 179 ₆ by using the second expansion mechanisms 195 ₁ to 195 ₆composing the second parallel link mechanism 134 via the stagecontroller 52, thereby precisely controlling the position/attitude, inthe six degrees of freedom (X, Y, Z, θx, θy, θz), of the reticle stageRST with desirable operational-characteristics and high rigidity.Because the reticle stage RST is driven by the second parallel linkmechanism 134, such a driver to drive the reticle stage WST as a linearmotor and a stage base (reticle base level block) to support the reticlestage RST are unnecessary. Also, it is unnecessary to provide a Z-tiltdriving mechanism, etc., on the reticle stage RST. Therefore, it ispossible to make the reticle stage RST small and lightweight.

Furthermore, in the exposure apparatus 130 of the present embodiment, asupporting mechanism (140, 142, 144) supports the projection opticalsystem PL fixed thereto on the floor surface FD where the exposureapparatus 130 is installed. Therefore, after the projection opticalsystem PL is adjusted to take a desirable position and attitude at theinitial adjustment in advance and is fixed in such a state by thesupporting mechanism, the main controller 50 controls theposition/attitude, in the six degrees of freedom (X, Y, Z, θx, θy, θz),of the wafer stage WST and the reticle stage RST as described above. Asits result, the relative position, in six degrees of freedom, of thewafer stage WST (wafer W) with respect to the projection optical systemPL and the relative position, in six degrees of freedom, of the reticlestage RST (reticle R) with respect to the projection optical system PLcan be controlled. Also, the position/attitude, in six degrees offreedom, of the wafer W are measured with respect to the projectionoptical system PL, as reference, by the wafer interferometer system(24Wx₁, 24Wx₂, 24Wy) and the focus sensor 73 that are fixed on thelens-barrel level block 144 or the projection optical system PL that areindependent from the wafer stage WST and the reticle stage RST regardingvibrations. Therefore, it is possible to perform precise measurements.

In the present embodiment, because the first expansion mechanisms 194 ₁to 194 ₆ and the second expansion mechanisms 195 ₁ to 195 ₆ eachcomprise an air cylinder and a shaft motor that are arranged mutually inseries, the main controller 50 can drive the wafer stage WST and thereticle stage RST coarsely and by larger distances by controlling theair pressure of the air cylinder and also finely by the shaft motor. Asa result, the main controller 50 can precisely adjust thepositions/attitudes, in six degrees of freedom, of the wafer stage andthe reticle stage, and then their relative positions with respect to theprojection optical system PL in a short time.

In the present embodiment, in the same manner as the first embodiment,because the first rods 178 ₁ to 178 ₆ and the second rods 179 ₁ to 179 ₆each comprise an air pad to support the mover of the shaft motor withrespect to its stator in a non-contact manner, in controlling theexpansions/contractions of the first rods 178 ₁ to 178 ₆ and the secondrods 179 ₁ to 179 ₆ by expansion mechanisms, friction that works as anon-linear component can be avoided. Therefore, the positions/attitudes,in six degrees of freedom, of the wafer stage WST and the reticle stageRST can be more precisely controlled. Note that in this case, a magneticbearing unit may be used instead of the air pad.

In the exposure apparatus 130 of the present embodiment, in the samemanner as the first embodiment, much larger thrust can be generatedcompared with, e.g. usual linear motor, etc., and it is possible to makeit smaller than a hydraulic cylinder, etc. Also, the parallel linkmechanism 132, 134 of which each rod comprises an air cylinder and ashaft motor are suitable for the exposure apparatus 130 because makingthe exposure apparatus small and more lightweight and improving itsoutput at the same time.

In the exposure apparatus 130 of the present embodiment, the maincontroller 50 statically adjusts the relative position, with respect tothe projection optical system PL, of at least one of the wafer stage WSTand the reticle stage RST by using air cylinders composing the first andsecond expansion mechanisms and can suppress vibrations by using shaftmotors. In this way, it is possible to adjust the relative position,with respect to the projection optical system PL, of at least one of thewafer stage WST and the reticle stage RST and suppress vibrations causedby the expansion/contraction-drive of the rods.

The main controller 50 can suppress vibrations of low frequency bycontrolling the air pressure of the air cylinders composing the firstand second expansion mechanisms and isolate high frequency vibrations bycontrolling currents to the shaft motors. Therefore, low frequencyvibrations in the wafer base level block 38 and the reticle base levelblock 12 due to a reaction caused by the drive of each stage can besuppressed and fine vibrations from the floor surface, i.e. highfrequency vibrations, can be isolated.

Furthermore, the main controller 50 can isolate high frequencyvibrations by controlling currents to the shaft motors, thereby beingable to isolate fine vibrations from the floor surface, i.e. highfrequency vibrations.

In the exposure apparatus 130 of the present embodiment, a number ofdevices described above make the wafer stage WST and the reticle stageRST lightweight, improve controllability of their positions and itscharacteristics of suppressing vibrations of the units and isolatingvibrations of the floor, and make it possible to manufacture highlyintegrated semiconductor devices, which have finer line widths, withhigh yield. Also, the exposure apparatus of the present embodiment canperform exposure with high resolution with using F₂ laser light or anenergy beam of shorter wavelength in the atmosphere filled with a gassuch as helium.

Incidentally, although the second embodiment described a case where thepositions/attitudes, in six degrees of freedom, of the wafer stage WSTand the reticle stage RST are controlled by the parallel linkmechanisms, the present invention is not limited to this, not tomention. For example, the position/attitude, in six degrees of freedom,of only one of the wafer stage WST and the reticle stage RST may becontrolled by the parallel link mechanism while the other is driven inthe degrees of freedom X, Y, θz by using a linear motor, a planar motor,etc., and the position/attitude, in the degrees of freedom Z, θx, θy, ofan object (wafer or reticle) mounted on the stage is controlled by aZ-leveling mechanism provided on the stage.

In another case, for at least one of the wafer stage WST and the reticlestage RST, the positions/attitudes in at least three degrees of freedom,e.g. X, Y, θz, may be controlled by the parallel link mechanismscomprising three expandable rods. In this case, a driver such as alinear motor, a stage base and the like of at least one of the waferstage WST and the reticle stage RST are unnecessary. Note that tocontrol the positions/attitudes in six degrees of freedom of the waferand reticle, it is necessary to provide a mechanism (e.g., a Z-tiltdriving mechanism) and the like to drive the other three degrees offreedom (e.g., Z, θx, θy) of the object (wafer or reticle) mounted onthe stage.

Incidentally, although the second embodiment described a case where asupporting mechanism (140, 142, 144) supports the projection opticalsystem PL fixed thereto on the floor surface FD, a parallel linkmechanism comprising at least three expandable rods may support theprojection optical system PL like the first embodiment. In this case,the initial adjustment of the projection optical system PL can be easilyperformed by controlling the expansion mechanism of each rod. Afterthat, the projection optical system PL can be supported to take adesirable and fixed position/attitude by keeping the length of each rodby its expansion mechanism. Then by controlling the positions/attitudesof both the stages and adjusting the relative positions, in at leastthree degrees of freedom, of both the stages with respect to theprojection optical system PL, the whole adjustment can be satisfactorilyperformed. In this case, an expansion mechanism comprising an aircylinder like the above expansion mechanisms is preferred. By such anexpansion mechanism, the initial position/attitude of the projectionoptical system PL can be easily adjusted by adjusting the insidepressure of the air cylinder.

Furthermore, although the second embodiment described a case where thebase member 136 of the first link mechanism 132 to control theposition/attitude of the wafer stage WST and the base member 154 of thesecond link mechanism 134 to control the position/attitude of thereticle stage RST are separate, these base members may be one member. Inthis case, if a link mechanism supports the projection optical systemPL, the base member of the link mechanism and at least one of the basemember 136 and the base member 154 may be one member.

Note that the parallel link mechanisms of the first and secondembodiments are examples and that parallel link mechanisms, which theexposure apparatus of the present invention can use, are not limited tothose.

The exposure apparatus of the present embodiments is made by assemblingvarious sub-systems comprising elements in the claims of the presentpatent application while keeping mechanical precision, electricprecision, and optical precision. To ensure the precision, after andbefore the assembly, adjustment to achieve the optical precision isperformed to its optical system; adjustment to achieve the mechanicalprecision is to its mechanical system, and adjustment to achieve theelectric precision is to its electric system. A process of assemblingvarious sub-systems into an exposure apparatus includes mechanicalconnection among the sub-systems, connection of electric circuits, andconnection of tubes of air pressure circuits. Needless to say, beforethe process of assembling various sub-systems into an exposureapparatus, each sub-system should be assembled. After the process ofassembling various sub-systems into an exposure apparatus, comprehensiveadjustment is performed to ensure various kinds of precision of thewhole exposure apparatus. Note that it is preferable to make an exposureapparatus in a clean room where the temperature, the degree ofcleanness, and the like are controlled.

Incidentally, although the present embodiments described a case wherethe present invention is employed in a scanning exposure apparatus of astep-and-scan method, the present invention is not limited to that. Thepresent invention can be suitably employed in a stationary-exposure-typesuch as an exposure apparatus (stepper) of a step-and-repeat method andalso in an exposure apparatus of a step-and-switch method such as amirror projection aligner.

Incidentally, although the present embodiments described a case wherelight, of which the wavelength is in the rang of about 120 nm to about180 nm and belongs to vacuum ultraviolet region, F₂ laser light, Kr₂laser light, Ar₂ laser, ArF excimer laser light, or the like is used asthe exposure illumination light. An ultraviolet emission light (g-line,i-line, etc.) from ultra-high pressure mercury lamp, KrF excimer laserlight, harmonic wave from copper vapor laser or YAG laser, or the likemay be used.

Furthermore, as a vacuum ultraviolet light, ArF excimer laser light orF₂ laser light is used. However, a higher harmonic wave may be usedwhich is obtained with wavelength conversion into ultraviolet by usingnon-linear optical crystal after amplifying a single wavelength laserlight, infrared or visible, emitted from a DFB semiconductor laserdevice or a fiber laser by a fiber amplifier having, for example, erbium(or erbium and ytterbium) doped.

For example, considering that the oscillation wavelength of a singlewavelength laser is in the range of 1.51 to 1.59 um, aneight-time-higher harmonic wave of which the wavelength is in the rangeof 189 to 199 nm or a ten-time-higher harmonic wave of which thewavelength is in the range of 151 to 159 nm is emitted. Especially, whenthe oscillation wavelength is in the range of 1.544 to 1.553 um, aneight-time-higher harmonic wave of which the wavelength is in the rangeof 193 to 194 nm, that is, almost the same as ArF excimer laser light(ultraviolet light) is obtained, and when the oscillation wavelength isin the range of 1.57 to 1.58 um, a ten-time-higher harmonic wave ofwhich the wavelength is in the range of 157 to 158 nm, that is, almostthe same as F₂ laser light (ultraviolet light) is obtained.

Furthermore, when the oscillation wavelength is in the range of 1.03 to1.12 um, a seven-time-higher harmonic wave of which the wavelength is inthe range of 147 to 160 nm is emitted, and, especially, when theoscillation wavelength is in the range of 1.099 to 1.106 um, aseven-time-higher harmonic wave of which the wavelength is in the rangeof 157 to 158 nm, that is, almost the same as F₂ laser light(ultraviolet light) is obtained. In this case, for example,ytterbium-doped fiber laser can be employed as the single wavelengthlaser.

Furthermore, the present invention can be applied to an scanningexposure apparatus employing EUV (Extreme Ultraviolet) light, of whichthe wavelength is in the range of 5 to 50 nm, as an exposureillumination light. In such an exposure apparatus using EUV light, anall-reflection-type optical system and a reflection-type reticle areemployed.

Also, the present invention can be applied not only to a light exposureapparatus described above but also to an exposure apparatus using acharged particle beam such as an electron beam.

Moreover, the present invention can be applied not only to micro devicessuch as semiconductor devices but also to the production of reticles ormasks used by a light exposure apparatus, EUV (Extreme Ultraviolet)exposure apparatus, X-ray exposure apparatus and electron beam exposureapparatus, and an exposure apparatus that transfers a circuit patternonto a glass substrate or silicon wafer. Incidentally, in an exposureapparatus using DUV (far ultraviolet) light or VUV (vacuum ultraviolet)light, a transmission-type reticle is employed in general. And as thesubstrate of the reticle, quartz glass, quartz glass with fluorinedoped, fluorite, magnesium fluoride, or quartz crystal is employed. Andan X-ray exposure apparatus or electron beam exposure apparatus of aproximity method employs a transmission-type mask (stencil-mask,membrane-mask), and as the substrate of the mask, silicon wafer or thelike is employed.

Note that the present invention can be applied not only to a waferexposure apparatus used in the production of semiconductor devices butalso to an exposure apparatus that transfers a device pattern onto aglass plate and is used in the production of displays such as liquidcrystal display devices, an exposure apparatus that transfers a devicepattern onto a ceramic plate and is used in the production of thinmagnetic heads, and an exposure apparatus used in the production ofpick-up devices (CCD, etc.).

In addition, the parallel link mechanism according to the presentinvention can be applied not only to an exposure apparatus but alsopreferably to any apparatus of which the miniaturization and lightening,and the improvement of the output are necessary and which needs toprecisely control the position/attitude of a body to be driven.

A Device Manufacturing Method

The embodiment of the method of manufacturing a device by using theabove exposure apparatus in lithography processes will be describednext.

FIG. 18 is a flow chart for the manufacture of a device (a semiconductorchip such as IC or LSI, liquid crystal panel, CCD, thin magnetic head,micro machine, or the like) in this embodiment. As shown in FIG. 18, instep 201 (design step), function/performance design for a device (e.g.,circuit design for a semiconductor device) is performed to performpattern design to implement the function. In step 202 (maskmanufacturing step), a mask on which the designed circuit pattern isformed is manufactured. In step 203 (wafer manufacturing step), a waferis manufacturing by using a silicon material or the like.

In step 204 (wafer processing step), an actual circuit and the like areformed on the wafer by lithography or the like using the mask and waferprepared in steps 201 to 203, as will be described later. In step 205(device assembly step), a device is assembled by using the waferprocessed in step 204. Step 205 includes processes such as dicing,bonding, and packaging (chip encapsulation).

Finally, in step 206 (inspection step), a test on the operation of thedevice, durability test, and the like are performed. After these steps,the device is completed and shipped out.

FIG. 19 is a flow chart showing a detailed example of step 204 describedabove in manufacturing the semiconductor device. Referring to FIG. 19,in step 211 (oxidation step), the surface of the wafer is oxidized. Instep 212 (CVD step), an insulating film is formed on the wafer surface.In step 213 (electrode formation step), an electrode is formed on thewafer by vapor deposition. In step 214 (ion implantation step), ions areimplanted into the wafer. Steps 211 to 214 described above constitute apre-process for each step in the wafer process and are selectivelyexecuted in accordance with the processing required in each step.

When the above pre-process is completed in each step in the waferprocess, a post-process is executed as follows. In this post-process,first of all, in step 215 (resist formation step), the wafer is coatedwith a photosensitive agent. In step 216, the circuit pattern on themask is transferred onto the wafer by the above exposure apparatus andmethod. In step 217 (developing step), the exposed wafer is developed.In step 218 (etching step), an exposed member on a portion other than aportion where the resist is left is removed by etching. In step 219(resist removing step), the unnecessary resist after the etching isremoved.

By repeatedly performing these pre-process and post-process, amultiple-layer circuit pattern is formed on each shot-area of the wafer.

According to the method of manufacturing a device of the presentembodiment, because exposure is performed by using an exposure apparatus10 or 130 of the above embodiments in the exposure process (step 216)and exposure precision is improved, a highly integrated device ismanufactured with high yield.

INDUSTRIAL APPLICABILITY

As has been described above, because the parallel link mechanismaccording to the present invention can realize the miniaturization andlightening, it is suitably applicable to an exposure apparatus. Inaddition, the exposure apparatus according to the present invention issuitable to precisely form a fine pattern composed of multi-layers on asubstrate such as a wafer by transferring each layer. Furthermore, themethod of manufacturing a device according to the present invention issuitable for manufacturing a device having a fine pattern.

1. An exposure apparatus that transfers a predetermined pattern onto asubstrate, the exposure apparatus comprising: a projection systemlocated between the predetermined pattern and the substrate to projectthe predetermined pattern to the substrate, the projection system beinga reflection type projection system; a sensor coupled to the projectionsystem and configured to detect a surface of the substrate; a firstparallel link mechanism configured to support the projection system suchthat its attitude is controllable; and a controller configured tocontrol the first parallel link mechanism to adjust an attitude of theprojection system in accordance with a condition of a surface on whichthe exposure apparatus is disposed.
 2. An exposure apparatus accordingto claim 1, further comprising: a substrate stage that holds thesubstrate, and a second parallel link mechanism that controlsposition/attitude, in at least three degrees of freedom, of thesubstrate stage.
 3. An exposure apparatus according to claim 2, whereinthe second parallel link mechanism comprises a first base member, atleast three expandable first rods that link the first base member andthe substrate stage, and first expansion mechanisms that are arranged inthe respective first rods and expand/contract the respective first rods.4. An exposure apparatus according to claim 3, wherein the secondparallel link mechanism comprises six of the first rods and controlsposition/attitude, in six degrees of freedom, of the substrate stage byexpansion/contraction of each first rod.
 5. An exposure apparatus thattransfers a predetermined pattern onto a substrate, the exposureapparatus comprising: an exposure main portion that transfers thepattern; and a parallel link mechanism that supports the exposure mainportion such that its attitude is controllable, the parallel linkmechanism comprising an air cylinder configured to move the exposuremain portion coarsely and an electromagnetic linear motor configured tomove the exposure main portion finely.
 6. An exposure apparatusaccording to claim 5, wherein the exposure main portion furthercomprises a projection optical system that projects the pattern onto thesubstrate.
 7. An exposure apparatus that transfers a predeterminedpattern of a mask onto a substrate, the exposure apparatus comprising: aprojection system located between the mask and the substrate and adaptedto project the predetermined pattern to the substrate; a mask stageadapted to hold the mask; a support mechanism that supports theprojection system; and a parallel link mechanism comprising three rodsadapted to control a relative position, in at least three degrees offreedom, of the mask stage, the parallel link mechanism linking the maskstage and a base member different from the support mechanism.
 8. Anexposure apparatus according to claim 7, wherein the parallel linkmechanism comprises at least three expandable rods that link the basemember and the mask stage, and expansion mechanisms that are arranged inthe respective rods and expand/contract the respective rods.
 9. Anexposure apparatus according to claim 8, wherein the parallel linkmechanism comprises six of the rods and controls position/attitude, insix degrees of freedom, of the mask stage by expansion/contraction ofeach rod.
 10. An exposure apparatus according to claim 7, wherein theparallel link mechanism comprises an air cylinder and an electromagneticlinear motor that are arranged in parallel or in series with each other.11. An exposure apparatus according to claim 10, wherein the parallellink mechanism further comprises a bearing unit that supports a mover ofthe electromagnetic linear motor with respect to its stator innon-contact manner.
 12. An exposure apparatus according to claim 11,wherein the bearing unit is a gas static pressure bearing unit.
 13. Anexposure apparatus according to claim 12, wherein the gas staticpressure bearing unit comprises a differential exhaust mechanism.
 14. Anexposure apparatus according to claim 11, wherein the bearing unit is amagnetic bearing unit.
 15. An exposure apparatus according to claim 10,the exposure apparatus further comprising: a substrate stage that holdsthe substrate; and a controller to statically adjust a position of atleast one of the mask stage and the substrate stage by use of the aircylinder and suppress vibrations by use of the electromagnetic linearmotor.
 16. An exposure apparatus according to claim 5, furthercomprising: a controller to insulate high-frequency vibrations bycontrolling an electric current supplied to the electromagnetic linearmotor.
 17. An exposure apparatus according to claim 6, furthercomprising: a supporting mechanism that supports the projection opticalsystem to be in a fixed state on a floor surface where the exposure mainportion is mounted.
 18. An exposure apparatus according to claim 5,wherein the exposure main portion comprises a mask stage that holds amask on which the pattern is formed, and the parallel link mechanismcontrols relative position, in three degrees of freedom, of the maskstage.
 19. An exposure apparatus according to claim 18, wherein theparallel link mechanism comprises a base member, at least threeexpandable rods that link the base member and the mask stage, andexpansion mechanisms that are arranged in the respective rods andexpand/contract the respective rods.
 20. An exposure apparatus accordingto claim 19, wherein the parallel link mechanism comprises six of therods and controls position/attitude, in six degrees of freedom, of themask stage by expansion/contraction of each rod.
 21. An exposureapparatus according to claim 5, wherein the exposure main portioncomprises a substrate stage that holds the substrate and a first stagebase that supports the substrate stage so as to be movable, and theparallel link mechanism controls relative position, in three degrees offreedom, of the first stage base.
 22. An exposure apparatus according toclaim 21, wherein the parallel link mechanism comprises a first basemember, at least three expandable first rods that link the first basemember and the first stage base, and first expansion mechanisms that arearranged in the respective first rods and expand/contract the respectivefirst rods.
 23. An exposure apparatus according to claim 1, furthercomprising: a position detector that is fixed on the projection systemand detects positional relationship, in six degrees of freedom, betweenthe substrate and the projection system.
 24. An exposure apparatusaccording to claim 5, wherein the exposure main portion comprises a maskstage that holds a mask, on which the pattern is formed, and a secondstage base that supports the mask stage so as to be movable, and theparallel link mechanism also controls position/attitude, in threedegrees of freedom, of the second stage base.
 25. An exposure apparatusaccording to claim 24, wherein the parallel link mechanism comprises asecond base member, at least three expandable second rods that link thesecond base member and the second stage base, and second expansionmechanisms that are arranged in the respective second rods andexpand/contract the respective second rods.
 26. An exposure apparatusaccording to claim 24, further comprising: a controller to staticallyadjust a position of the first stage base by use of the air cylinder andsuppress vibrations by use of the electromagnetic linear motor.
 27. Anexposure apparatus according to claim 5, further comprising: acontroller to suppress low-frequency vibrations by controllingair-pressure of the air cylinder and insulate high-frequency vibrationsby controlling an electric current of the electromagnetic linear motor.28. An exposure apparatus according to claim 21, wherein a plurality ofstages are mounted on the first stage base.
 29. An exposure apparatusaccording to claim 2, further comprising: a mask stage that holds amask, on which the pattern is formed; a stage base that supports themask stage so as to be movable; and a third parallel link mechanism thatcontrols position/attitude, in three degrees of freedom, of the stagebase.
 30. An exposure apparatus according to claim 5, furthercomprising: a chamber that houses at least one part of the exposure mainportion to be sealed from the outside atmosphere and so as for itsattitude to be allowed to change.
 31. An exposure apparatus according toclaim 30, further comprising: a vacuum exhaust system and a gas supplysystem to purge non-active gas into the chamber.
 32. A method of makingan exposure apparatus to transfer a pattern of a mask onto a substrate,comprising the steps of: providing a mask stage adapted to hold themask; providing a projection optical system adapted to project a patternof the mask onto a substrate; providing a substrate stage adapted tohold the substrate; providing a first parallel link mechanism thatsupports the projection optical system such that an attitude of theprojection optical system is controllable; and providing a secondparallel link mechanism that supports at least one of the mask stage andthe substrate stage such that relative position, in at least threedegrees of freedom, of at least one of the mask stage and the substratestage with respect to the projection optical system is controllable, thesecond parallel link mechanism being isolated from the first parallellink mechanism.
 33. A method of making an exposure apparatus to transfera pattern of a mask onto a substrate, comprising the steps of: providinga mask stage adapted to hold the mask; providing a projection opticalsystem adapted to project a pattern of the mask onto a substrate;providing a substrate stage adapted to hold the substrate; providing afirst parallel link mechanism that supports the substrate stage, thefirst parallel link mechanism being connected to a first base member;and providing a second parallel link mechanism that supports the maskstage, the second parallel link mechanism being connected to a secondbase member different from the first base member, the second base memberbeing larger than the first base member.
 34. A method of manufacturing adevice with a lithography process, wherein in the lithography process,exposure is performed using an exposure apparatus according to claim 1.35. An exposure apparatus according to claim 1, wherein the projectionsystem optically projects the predetermined pattern.
 36. A methodaccording to claim 33, wherein the first parallel link mechanismsupports the substrate stage via a substrate stage base that supportsthe substrate stage to be movable, and the second parallel linkmechanism supports the mask stage via a mask stage base that supportsthe mask stage to be movable.
 37. A method according to claim 32,wherein the projection optical system is a reflection type projectionoptical system.
 38. A method according to claim 33, wherein theprojection optical system is a reflection type projection opticalsystem.
 39. An exposure apparatus that transfers a predetermined patternonto a substrate, the exposure apparatus comprising: a projection systemlocated between the predetermined pattern and the substrate to projectthe predetermined pattern to the substrate; a sensor coupled to theprojection system and configured to detect a surface of the substrate; afirst parallel link mechanism comprising a plurality of rods configuredto support the projection system such that an attitude of the projectionsystem is controllable, the rods connected to an outer portion of theprojection system; and a controller configured to control the firstparallel link mechanism to adjust an attitude of the projection systemin accordance with a condition of a surface on which the exposureapparatus is disposed.
 40. An exposure apparatus according to claim 39,wherein the parallel link mechanism supports the projection system froma floor side.
 41. An exposure apparatus according to claim 39, whereinthe three rods extend in non-parallel directions.
 42. An exposureapparatus according to claim 1, wherein the projection system comprisesa flange disposed above the sensor.
 43. An exposure apparatus accordingto claim 1, wherein the sensor comprises an alignment sensor.
 44. Anexposure apparatus according to claim 1, wherein the sensor comprises anautofocus sensor.
 45. An exposure apparatus according to claim 39,wherein the projection system comprises a flange disposed above thesensor.
 46. An exposure apparatus according to claim 39, wherein thesensor comprises an alignment sensor.
 47. An exposure apparatusaccording to claim 39, wherein the sensor comprises an autofocus sensor.48. An exposure apparatus according to claim 1, wherein the firstparallel link mechanism comprises three rods configured to support theprojection system.
 49. An exposure apparatus according to claim 39,wherein the first parallel link mechanism comprises three rodsconfigured to support the projection system.
 50. An exposure apparatusaccording to claim 1, wherein the controller is configured to controlthe first parallel link mechanism in accordance with a profile of afloor on which the exposure apparatus is disposed.
 51. An exposureapparatus according to claim 1, wherein the controller is configured tocontrol the first parallel link mechanism in accordance with adeformation of a floor on which the exposure apparatus is disposed. 52.An exposure apparatus according to claim 39, wherein the controller isconfigured to control the first parallel link mechanism in accordancewith a profile of a floor on which the exposure apparatus is disposed.53. An exposure apparatus according to claim 39, wherein the controlleris configured to control the first parallel link mechanism in accordancewith a deformation of a floor on which the exposure apparatus isdisposed.